WO2014084184A1

WO2014084184A1 - Elastic body for actuator, and piezoelectric actuator

Info

Publication number: WO2014084184A1
Application number: PCT/JP2013/081697
Authority: WO
Inventors: 清水　潔; 茂樹蒲原; 金田　宏; 伊藤　雅章; 篤史久米; 直人奥山
Original assignee: 株式会社ダイセル
Priority date: 2012-11-29
Filing date: 2013-11-26
Publication date: 2014-06-05
Also published as: TW201436446A; JPWO2014084184A1; CN104956584A; EP2928064A4; US20150326147A1; EP2928064A1

Abstract

　An elastic body (43) formed from a crystalline resin is fixed to a piezoelectric element (42) for generating vibrations using the application of an AC voltage, is used in contact with a movable body (45), and flexurally vibrates owing to the vibrations of the piezoelectric element (42), thereby driving the movable body (45). Teeth (43b) may be formed on the opposite side of the elastic body (43) to the side on which the piezoelectric element (42) is fixed. The crystalline resin may be a polyaryl ketone resin or a polyphenylene sulfide resin. The piezoelectric actuator exhibits superior flexural vibration transmission properties. Furthermore, if a displacement enlargement element for a displacement enlargement piezoelectric actuator is formed from the crystalline resin, the displacement by the expansion and contraction of the piezoelectric element can be greatly enlarged. Moreover, if a resonance member of a Langevin transducer is formed from the crystalline resin, the surface thereof can rapidly be made to vibrate, even using a low current (or a low voltage).

Description

Elastic body for actuator and piezoelectric actuator

The present invention relates to an elastic body for an actuator using ultrasonic vibration by an electromechanical transducer such as a piezoelectric element, and a piezoelectric actuator provided with the elastic body.

An ultrasonic motor is known as a piezoelectric actuator using a piezoelectric element. The ultrasonic motor is a motor that uses a piezoelectric element that is an electromechanical variable element as an ultrasonic vibrator. Compared to electromagnetic motors, ultrasonic motors do not require windings, are simple in structure, have low speed and high torque, have excellent responsiveness and controllability, and can be driven minutely and precisely. It is widely used in optical equipment devices. There are a linear type and a rotor type in the ultrasonic motor, and the ultrasonic vibration from the vibrating body is converted into a linear motion or a rotational motion.

FIG. 1 is a schematic side view of a rotor type ultrasonic motor, and FIG. 2 is a schematic perspective view of an elastic body constituting the rotor type ultrasonic motor of FIG. The ultrasonic motor 1 is regularly formed on the disk-shaped (or ring-shaped) piezoelectric element 2 having the same outer diameter as the outer diameter of the piezoelectric element 2 and along the outer periphery. A stator 4 to which a ring-shaped elastic body (comb-shaped elastic body) 3 having a comb-shaped convex portion (comb-toothed portion) 3a is fixed; A disk-shaped (or ring-shaped) rotor (rotating body or moving body) 5 having the same outer diameter as that of the elastic body is provided. In the ultrasonic motor 1, the stator 4 composed of the piezoelectric element (piezo element) 2 and the comb-like elastic body 3 is a fixed member, whereas the rotor 5 is rotatably arranged. The ultrasonic vibration generated by the piezoelectric element 2 is converted into the rotational motion of the rotor 5 via the comb-like elastic body 3. Specifically, the piezoelectric element 2 is formed of piezoelectric ceramics that generate distortion when a voltage is applied. When an AC voltage (frequency voltage) is applied, the piezoelectric element 2 regularly repeats distortion and recovery (extension and contraction). To vibrate ultrasonically. On the other hand, in the comb-like elastic body 3 fixed to the piezoelectric element, the surface traveling wave (longitudinal wave and transverse wave) transmitted along the surface of the elastic body is combined with the ultrasonic vibration from the piezoelectric element. Rayleigh wave). As a result, elliptical motion (bending vibration) occurs on the surface of the elastic body, and the rotor 5 in pressure contact with the elastic body rotates. When such bending vibration is used, the complex elastic modulus in the bending direction is important, and the material is selected from such a viewpoint.

Generally, a metal material is used as the elastic body because it can generate a surface traveling wave without absorbing ultrasonic vibration from a piezoelectric element. However, an elastic body made of metal has a high specific gravity and is hard, so it has low vibration characteristics, low formability, and is difficult to downsize. There are also disadvantages such as a point of deterioration, a point of deterioration due to rust, a point of difficulty in improving the characteristics by blending additives, and a point of inability to ensure insulation. As an elastic body other than metal, unlike metal, it has viscosity, so it is not suitable as a vibrator by absorbing vibration, or an elastic body made of plastic is proposed, although it has not been put to practical use. Has been.

Japanese Patent Laid-Open No. 5-300764 (Patent Document 1) discloses a moving body that contacts an elastic body by applying elliptical motion generated in an elastic body that applies a frequency voltage to the electromechanical conversion element and is joined to the electromechanical conversion element. A drive mechanism is disclosed in which a side of the elastic body that contacts the moving body is formed of resin. In this document, an elastic body made of metal is further interposed between an elastic body made of resin and the electromechanical conversion element.

However, even in this drive mechanism, since the elastic body contains metal, vibration is not sufficient and rust is generated. Furthermore, the details of the resin are not described in this document. Further, since the resin normally absorbs ultrasonic vibration as compared with the metal material, the vibration transmission is low. Furthermore, since the elastic body is a friction drive type that is brought into contact with the moving body, frictional heat is generated and heat resistance is required. However, the resin material has lower heat resistance than the metal material.

Japanese Patent Publication No. 7-89746 (Patent Document 2) discloses a stator composed of a piezoelectric element and an elastic body excited by the piezoelectric element, and a surface of ultrasonic vibration generated in the stator in pressure contact with the stator. In a surface wave motor comprising a mover that is an elastic body that moves on the surface of the stator by a traveling wave, at least one of the two elastic bodies is formed of a synthetic resin material. There is disclosed a surface wave motor in which a vibrating portion having a surface to which the elastic body is pressed, a supporting portion extending from the vibrating portion, and a held portion provided on the outer periphery of the supporting portion are integrally molded. Yes.

However, even in this document, the synthetic resin material includes engineering plastic, and a material having a low elastic modulus is preferable. An elastic modulus of about 1/10 for a piezoelectric element and an elastic modulus of about 1/20 for a metal. However, details of the synthetic resin are not described.

Japanese Patent Laid-Open No. 2006-311794 (Patent Document 3) includes an electromechanical transducer that expands and contracts when a voltage is applied, and a movable body that is slidably supported and coupled to the electromechanical transducer. And a movable body support member that is displaced together with the electromechanical conversion element. The drive device moves the movable body along the movable body support member by expansion and contraction of the electromechanical conversion element. A drive device is disclosed in which the material is a fiber reinforced resin composite, and the synthetic resin material constituting the fiber reinforced resin composite is a liquid crystal polymer or polyphenylene sulfide. Specifically, the moving support member (drive shaft) corresponding to the elastic body has a rod shape, and one end thereof and the end of the rod-shaped piezoelectric element are bonded and fixed, and the moving support member has a length due to expansion and contraction of the piezoelectric element. By displacing along the direction, the moving body supported by the moving support member is moved with a predetermined frictional force. That is, the mechanism for moving the moving body applies a sawtooth waveform pulse voltage consisting of a sudden rising part and a gentle falling part to strengthen the reciprocating motion in the length direction of the drive shaft, The moving body is moved according to the law.

However, this document does not describe a piezoelectric actuator that bends and vibrates the moving support member. Specifically, in the drive device of Patent Document 3, the piezoelectric element and the drive shaft do not come into surface contact, and the drive shaft moves the moving body by friction in a reciprocating motion in the length direction using sawtooth pulses. The drive shaft itself is not deformed. For this reason, it is presumed that the material constituting the drive shaft is mainly required to have rigidity for accurately transmitting the vibration of the piezoelectric element, and fibers are blended to maintain rigidity. That is, the drive mechanism of Patent Document 3 is a traveling wave type actuator, that is, a surface traveling wave (sinusoidal) generated by vibration of a piezoelectric element in a state where a piezoelectric element and a moving body are fixed in surface contact and fixed in surface contact. The driving principle is greatly different from an actuator that is elliptically moved by bending and deforming the elastic body itself using waves) (by bending the elastic body in conjunction with the vibration of the piezoelectric element). For this reason, the drive shaft of Patent Document 3 does not require the flexibility required for bending vibration, and the required characteristics are significantly different from an elastic body using bending vibration in an ultrasonic motor.

Japanese Patent Laid-Open No. 2001-327919 (Patent Document 4) discloses two or more composite material plates in which a plurality of highly elastic fibers are regularly oriented in the same direction in a base material. An acoustic vibration control material that is laminated so that the orientation directions of the high elastic fibers are orthogonal to each other is disclosed. This document describes, as the control material, a carbon fiber or SiC fiber reinforced plastic molding using a polyamide resin or an epoxy resin as a base material.

However, this acoustic vibration control material is intended to control the transmission direction of acoustic vibration, and does not describe flexural vibration of an elastic body.

Also, among piezoelectric actuators, depending on the application, such as a piezoelectric pump and a linear motor, in order to apply the vibration (or expansion / contraction) of the electromechanical conversion element as an actuator, a mechanism for expanding the displacement due to the vibration is required.

As a mechanism for expanding displacement caused by vibration of a piezoelectric element, a stacked piezoelectric actuator that expands displacement by stacking piezoelectric elements is known.

Japanese Patent No. 4353690 (Patent Document 5) discloses a laminated piezoelectric actuator in which piezoelectric ceramic layers and internal electrodes are alternately stacked, and the internal electrodes are connected every other layer, and the outer periphery of the internal electrode The amount of displacement of the portion continuously decreases from the inside to the outside of the outer peripheral portion, and the portion located in the vicinity of the outer peripheral portion of the internal electrode in the piezoelectric ceramic layer includes manganese, iron, chromium, tungsten A multilayer piezoelectric actuator is disclosed in which one or more components selected from the above are included more than other components.

However, the multilayer piezoelectric actuator is large in size and is not suitable for miniaturization.

Also, a piezoelectric actuator is known that applies the lever principle to mechanically amplify the movement of the piezoelectric element to expand the displacement.

In JP-A-60-81568 (Patent Document 6), in an amplification mechanism for amplifying and driving the movement of electrostriction or a piezoelectric element, one end in the expansion / contraction direction of the electrostriction or piezoelectric element is connected in common, And two lever arms as displacement amplification means respectively connected to the other end of the electrostrictive or piezoelectric element by a fulcrum, and a beam as displacement amplification means supported so as to be sandwiched between the other ends of the two lever arms. And a mechanical amplifying mechanism in which a working element as an output end is provided on the beam.

However, even such a mechanical amplification mechanism is not suitable for miniaturization because the mechanism is large and complicated.

On the other hand, a cymbal type or Mooney type piezoelectric actuator having a plate-like element provided with a gap and fixed to the piezoelectric element has been proposed as a displacement enlarging element of the piezoelectric element.

FIG. 3 is a schematic perspective view of a cymbal type piezoelectric actuator, and FIG. 4 is a schematic view for explaining a displacement mechanism of the cymbal type piezoelectric actuator in which a protrusion (claw portion) is formed.

In this piezoelectric actuator 11, a plate-like displacement enlarging element 13 having a ridge-like convex portion 13a formed by bending is fixed on a plate-like piezoelectric element 12 having a rectangular surface shape. The ridge-like convex portion 13a is formed at a substantially central portion in the length direction of the displacement enlarging element, and the cross-sectional shape in the direction perpendicular to the ridge line direction of the ridge-like convex portion is a trapezoidal shape or an arch shape, A gap 14 having a trapezoidal cross section is formed between the gap 12 and the gap 12. In the piezoelectric actuator having such a gap portion, the piezoelectric element 12 is formed of piezoelectric ceramics that are distorted when a voltage is applied. When an AC voltage (frequency voltage) is applied, the piezoelectric element 12 is regular in the surface direction. Repeats distortion and recovery (stretching movement). On the other hand, since a gap 14 is formed between the displacement magnifying element 13 and the piezoelectric element 12, the ridge-like convex part of the displacement magnifying element 13 is compared with the portion fixed to the piezoelectric element 12. Thus, the structure is easy to deform. Therefore, when the piezoelectric element 12 expands and contracts in the surface direction, the shape of the ridge-shaped convex portion of the displacement magnifying element 13 is deformed and displaced (moves up and down) in a direction perpendicular to the surface direction of the piezoelectric element.

For example, as shown in FIG. 4, in the cymbal type piezoelectric actuator 21 in which the protrusion 23 b is formed on the side of the ridge-shaped convex portion 23, the ridge is in a state where the piezoelectric element 22 is extended in the surface direction (FIG. Since the height of the convex portion 23a is low and the inclination of the side portion is small, the protrusion 23b stands up in a direction substantially perpendicular to the surface of the piezoelectric element. On the other hand, in the state in which the piezoelectric element 22 is contracted in the plane direction (FIG. 4B), the height of the ridge-like convex portion 23a is high and the inclination of the side portion is large. Sleeps almost parallel to the surface. That is, the protrusion repeats the displacement motion between the standing state and the sleeping state due to the vibration of the piezoelectric element. Therefore, the cymbal type piezoelectric actuator provided with the protrusion can be used as a drive mechanism that scrapes the non-vibrating body (moving body) in contact with the protrusion, and can also be used for a linear motor or the like.

In a conventional cymbal type piezoelectric actuator, a metal material is used as a displacement enlarging element because it can be displaced without absorbing expansion / contraction of the piezoelectric element (or without bending due to expansion / contraction). However, since the elastic body made of metal has a high specific gravity and is hard, its own vibration property is low, its formability is low, and it is difficult to reduce the size, and the complex shape with protrusions is not productive. There are also disadvantages such as a point of deterioration, a point of deterioration due to rust, a point of difficulty in improving properties by blending additives, and a point of inability to ensure insulation.

Furthermore, Langevin vibrators are also known as piezoelectric actuators. The Langevin vibrator has a structure in which a piezoelectric crystal is sandwiched between two metal blocks, can resonate at a low frequency, and is widely used for generation and detection of ultrasonic waves. Various improvements have been attempted to date in order to further improve the performance of the Langevin vibrator.

JP-A-5-236598 (Patent Document 7) discloses a front mass formed of a highly rigid material, a piezoelectric ceramic that has one end joined to one end of the highly rigid material and converts an input electric signal into ultrasonic waves, A rear mass formed of a highly rigid material with one end joined to the other end of the piezoelectric ceramic, a bolt and a nut for fastening the front mass, the piezoelectric ceramic, and the rear mass together, and a water joined to the other end of the front mass. And a bolt-clamped Langevin vibrator with an acoustic matching plate having an acoustic matching plate for impedance matching with the front mass, wherein the acoustic matching plate has a glass transition temperature higher than the Curie temperature of the piezoelectric ceramic A Langevin transducer is disclosed. This document describes that the front mass and the rear mass are formed of a highly rigid material such as an aluminum alloy, a titanium alloy, or stainless steel.

In JP 2009-77130 A (Patent Document 8), a piezoelectric element, a pair of sandwiching members that sandwich the piezoelectric element, and one of the sandwiching members are fixed, and the hardness is lower than the one sandwiching member. An acoustic matching that is fixed to the buffer member and the other clamping member and has an ultrasonic transmission / reception unit at the end, and the value of the specific acoustic impedance indicates a value between the other clamping member and water An ultrasonic transducer comprising a member is disclosed. In this document, the backing plate as one clamping member and the front plate as the other clamping member are made of stainless steel, and the front plate is changed to an aluminum alloy that is lighter and softer than the backing plate. It is described that the Q value (a quantity representing the sharpness of resonance) can be reduced.

Japanese Patent Application Laid-Open No. 5-37999 (Patent Document 9) has a Langevin vibrator structure in which resonance blocks are provided symmetrically on both sides of a pair of piezoelectric vibrators, and the resonance block is made of a wideband ultrasonic wave made of plastic. A probe is disclosed. This document describes that the resonant block that provides broadband characteristics is composed of an epoxy compound material, and no other examples of plastic materials.

In JP 2007-274191 A (Patent Document 10), a front plate, a backing plate, and a piezoelectric ceramic body disposed between the front plate and the backing plate are integrally formed by a shaft core bolt. There is disclosed a fixed ultrasonic vibrator in which the front plate is made of resin. This document describes that a polypropylene resin excellent in machinability, a polycarbonate resin excellent in transparency, and an acrylic resin excellent in both performances are preferable as a material for the front plate.

However, in the ultrasonic vibrators of Patent Documents 7 to 10, the vibration speed on the surface is low and the output characteristics are not yet sufficient.

JP-A-5-300764 (Claim 1, FIGS. 1 and 3) Japanese Patent Publication No. 7-89746 (Claim 1, page 2, column 4, lines 19 to 21) JP 2006-31794 A (Claim 1, paragraphs [0004] to [0006] [0021] [0022]) JP 2001-327919 A (Claim 1, paragraphs [0010] [0022] [0026]) Japanese Patent No. 4353690 (Claim 1) JP-A-60-81568 (Claims) JP-A-5-236598 (Claims, paragraph [0003]) JP 2009-77130 A (Claims, paragraphs [0015] and [0047]) Japanese Patent Laid-Open No. 5-37999 (claims, paragraph [0012], examples) JP 2007-274191 A (Claims, paragraph [0013], Examples)

Therefore, an object of the present invention is to provide an elastic body for an actuator excellent in bending vibration (elliptical motion) transmission property, and a piezoelectric actuator provided with this elastic body, despite being formed of a resin.

Another object of the present invention is to provide an actuator elastic body excellent in moldability and light weight, excellent in downsizing and workability into a complicated shape, and a piezoelectric actuator provided with this elastic body.

Still another object of the present invention is to provide an actuator elastic body excellent in electrical insulation and corrosion resistance and a piezoelectric actuator provided with this elastic body.

Another object of the present invention is to provide a displacement enlarging element capable of greatly enlarging displacement due to vibration (or expansion / contraction) of an electromechanical transducer and a displacement enlarging piezoelectric actuator provided with the displacement enlarging element.

Still another object of the present invention is to provide a Langevin vibrator that can vibrate a surface at high speed even with a low current (or low voltage).

Another object of the present invention is to provide a Langevin transducer capable of reducing energy loss and transmitting and receiving ultrasonic waves with high efficiency.

Still another object of the present invention is to provide a Langevin vibrator that can be miniaturized even for use at a low frequency and can easily control the resonance wavelength.

As a result of intensive studies to achieve the above-mentioned problems, the present inventors have formed an elastic body for an actuator including an electromechanical conversion element such as a piezoelectric element from a crystalline resin, thereby forming the actuator. Nevertheless, the bending vibration transmission performance can be improved in an actuator that vibrates, the displacement due to vibration (or expansion and contraction) of an electromechanical transducer element can be greatly increased in a displacement expansion type actuator, and the low current (or The inventors have found that the surface can be vibrated at high speed even with a low voltage, and the present invention has been completed.

That is, the elastic body of the present invention is an elastic body that is fixed to an electromechanical transducer that expands and contracts when an AC voltage is applied, and is used in any of the following actuators (1) to (3): Contains resin.
(1) Actuator that is used in contact with a non-vibrating body, flexurally vibrates due to expansion and contraction of the electromechanical transducer, and drives the actuator itself or the non-vibrating body. (2) Displacement due to expansion and contraction of the electromechanical transducer. Actuator provided with a mechanism for enlarging (3) An actuator using a member for reducing the frequency of vibration due to expansion and contraction of the electromechanical transducer as at least one of the resonant members sandwiching the electromechanical transducer.

The electromechanical conversion element may be a piezoelectric element. The crystalline resin may be a polyaryl ketone resin or a polyphenylene sulfide resin. The elastic body of the present invention may further contain a filler (particularly a fibrous filler). The orientation direction of the fibrous filler may be parallel to the expansion / contraction direction of the electromechanical transducer. The fibrous filler may be at least one selected from the group consisting of carbon fiber, glass fiber, and aramid fiber. The fibrous filler may be a carbon fiber having an average fiber diameter of 0.1 to 50 μm and an average fiber length of 1 μm to 2 mm. The ratio of the filler may be about 10 to 60 parts by weight with respect to 100 parts by weight of the thermoplastic resin.

In the elastic body of the present invention, the actuator is an ultrasonic motor, and may have a plurality of convex portions for contacting the non-vibrating body on the side opposite to the side fixed to the piezoelectric element. In particular, in the elastic body of the present invention, the piezoelectric actuator may be a linear ultrasonic motor, and the cross-sectional shape of the plurality of convex portions may be a sawtooth shape. In the elastic body of the present invention, the piezoelectric actuator may be a rotor type ultrasonic motor and may have a comb tooth portion.

The elastic body of the present invention is an actuator having a mechanism in which the actuator expands displacement due to expansion and contraction of the piezoelectric element, and has a plate shape having a convex portion for forming a gap with the fixed piezoelectric element. Also good. The convex portion may be a ridge-shaped convex portion that extends in one direction and is bent or curved. The cross-sectional shape in a direction perpendicular to the ridge line direction of the ridge-shaped convex portion may be trapezoidal. The side part of the ridge-shaped convex part may have a protrusion.

The elastic body of the present invention may be a resonance member of a Langevin vibrator.

The present invention includes a piezoelectric actuator including a piezoelectric element and the elastic body.

The piezoelectric actuator of the present invention may be a rotor type ultrasonic motor that is used in contact with a rotating body, bends and vibrates due to expansion and contraction of the piezoelectric element, and rotates the actuator itself or the rotating body.

In the piezoelectric actuator of the present invention, the elastic body may be a displacement magnifying element and may be a cymbal type or Mooney type piezoelectric actuator.

The piezoelectric actuator of the present invention is a Langevin vibrator having a piezoelectric element and a pair of resonance members that sandwich the piezoelectric element, and at least one of the pair of resonance members is the elastic body. There may be. In general, when resin is used for one of the resonance members, it is assumed that the absorption of ultrasonic waves is greater than that of metal and does not vibrate. However, using the elastic body unexpectedly attenuates ultrasonic waves. It can vibrate with high efficiency. The pair of resonance members may contain different types of resins, but preferably contain the same kind of resin. The piezoelectric element and one resonance member and / or the other resonance member may be pressure-contacted (or pressure-bonded) with a joining means (screw or the like).

In this specification, the “elastic body” is formed of a composition containing a thermoplastic resin and a filler, is used by being fixed to an electromechanical transducer such as a piezoelectric element, and the vibration of the electromechanical transducer is used. This means a molded body capable of transmitting (extension and contraction), and is not limited to an elastic body of an ultrasonic motor, but is used to include a displacement enlarging element of a displacement enlarging actuator and a resonance member of a Langevin vibrator.

In the present invention, since the elastic body of the actuator that vibrates and vibrations contains a crystalline resin, the transmission of bending vibration (elliptical motion) can be improved even though it is formed of resin. In particular, the acoustic impedance difference with the electromechanical conversion element (particularly the piezoelectric element) can be suppressed, and the energy injection efficiency from the electromechanical conversion element can be increased, or the hysteresis of vibration can be suppressed and the loss can be minimized.

In the present invention, since the displacement enlarging element of the displacement enlarging actuator is formed of crystalline resin, the displacement due to expansion and contraction of the electromechanical transducer can be greatly expanded, and the crystalline resin and the fibrous filler are combined. Therefore, the displacement can be expanded as compared with the conventional metal material. In particular, although it has a specific gravity smaller than that of metal, it exhibits a displacement expansion function (vibration speed) equal to or higher than that of metal, has a high function per weight, and is suitable for applications that require weight reduction. For example, at the same resonance frequency, the size can be reduced as compared with a metal material. Furthermore, electrical insulation and corrosion resistance can be improved.

In the present invention, at least one of the pair of resonance members that sandwich the electromechanical conversion element of the Langevin vibrator is formed of a specific crystalline thermoplastic resin, so that a low current (or low voltage) is formed. ) But the surface can be vibrated at high speed, and the maximum vibration speed is high. In particular, in the present invention, energy loss can be remarkably reduced, so that ultrasonic waves can be transmitted and received with high efficiency. Further, in the present invention, it is small and excellent in lightness, and can be easily downsized even when used at a low frequency. Furthermore, in the present invention, the resonance wavelength (or sound velocity) can be easily controlled by adjusting the orientation and content of the fibrous filler.

Also, because it is made of resin, it is excellent in moldability and light weight, and can be downsized and processed into a complicated shape. Furthermore, electrical insulation and corrosion resistance can be improved.

FIG. 1 is a schematic side view of a rotor type ultrasonic motor. FIG. 2 is a schematic perspective view of an elastic body constituting the rotor type ultrasonic motor of FIG. FIG. 3 is a schematic perspective view of a cymbal type piezoelectric actuator. FIG. 4 is a schematic view for explaining the displacement mechanism of the cymbal type piezoelectric actuator having protrusions formed thereon. FIG. 5 is a schematic diagram for explaining a method of measuring the vibration speed of the elastic body. FIG. 6 is a schematic side view showing an example of the linear ultrasonic motor of the present invention. FIG. 7 is a schematic perspective view of a stator constituting the linear ultrasonic motor of FIG. FIG. 8 is a schematic cross-sectional view showing an example of the Langevin vibrator of the present invention. FIG. 9 is a graph showing the vibration speed of the elastic bodies obtained in Example 1 and Comparative Example 1. FIG. 10 is a graph showing the vibration speed of the elastic bodies obtained in Examples 2 and 3. FIG. 11 is a schematic perspective view of a cymbal type piezoelectric actuator manufactured in the example. FIG. 12 is a schematic diagram illustrating an experimental system for evaluating the Langevin vibrator of the example. FIG. 13 is a graph showing the relationship between the current and the vibration speed of the Langevin vibrator of the example.

[Elastic body for actuator]
The elastic body for an actuator of the present invention is fixed to a plate-like electromechanical conversion element (particularly a piezoelectric element for generating vibration by application of an AC voltage) that expands and contracts in a plane direction by application of an AC voltage. Ultrasonic motor, displacement expansion type actuator, Langevin vibrator). Since the elastic body contains a thermoplastic resin and a filler (particularly fibrous filler), the characteristics of various actuators can be improved.

(Crystalline resin)
Crystalline resin needs to have excellent vibration transmission properties. Specifically, both sides of a plate-shaped elastic body are fixed by sandwiching them between plate-shaped piezoelectric elements, and a resonant voltage is applied by applying a frequency voltage to the piezoelectric elements. When the voltage is increased, the maximum vibration speed is 300 mm / second or more, preferably 500 mm / second or more (for example, about 500 to 1500 mm / second), more preferably 700 mm / second or more (for example, 700 About 1000 mm / second). When the vibration speed is less than 300 mm / sec, vibration transmission to the moving body (or the driving performance of the elastic body itself) is low, and thus it is difficult to drive the moving body (or the elastic body itself).

In the present invention, the vibration speed of the crystalline resin can be measured by the method shown in FIG. That is, the crystalline resin is injection molded into a 10 cm square and 3 mm thick flat plate, and the obtained molded body is cut into 1 cm × 3 cm by cutting to obtain the resin elastic body 31. As shown in FIG. 5, the obtained resin elastic body 31 is sandwiched between two plate-like piezoelectric elements 32 (“C-123” manufactured by Fuji Ceramics Co., Ltd., 1 cm × 2 cm × 1 mm), and an adhesive (Huntsman Bonded with "Araldite (Araldite Standard)" manufactured by Japan Co., Ltd., cured and cured for 24 hours. Further, a copper wire 33 is soldered to the electrode of the piezoelectric element 32, and vibration is performed at the resonance frequency. Vibration is measured with a laser Doppler meter at the maximum speed of vibration. When the voltage is increased, an increase in the vibration speed is observed, but at or above a specific voltage corresponding to the mechanical properties of the resin elastic body, a stagnation or decrease in the vibration speed is observed, but the maximum speed is the vibration speed. .

The glass transition temperature (Tg) of the crystalline resin is 30 ° C. or higher. From the viewpoint of moldability, it is, for example, 50 to 450 ° C., preferably 70 to 350 ° C., more preferably 75 to 300 ° C. (especially 80 to 200 ° C.). Degree). Further, it may be 70 ° C. or higher, for example, 75 to 450 ° C., preferably 80 to 430 ° C. (eg 100 to 400 ° C.), more preferably 80 to 300 ° C. (especially 80 to 160 ° C.). May be. The glass transition temperature is preferably higher than the Curie temperature of the piezoelectric element. When a piezoelectric actuator such as an ultrasonic motor or a displacement expansion type actuator is operated, the temperature of the elastic body rises due to heat generation due to vibration, an increase in ambient temperature, heat storage due to friction, and the like, and the vibration performance decreases. Furthermore, the coefficient of friction of the elastic body also decreases, and the vibration transmission property to the moving body decreases. However, if the glass transition temperature is too low, such a decrease in vibration transmission property becomes significant. Furthermore, if the glass transition temperature is too low, the wear resistance at high temperatures also decreases, and wear and breakage are likely to occur at high temperatures due to frictional heat. On the other hand, if the glass transition temperature is too high, the molding temperature becomes high and approaches the decomposition temperature, which makes processing difficult. Since the crystalline resin used in the present invention has an appropriate elastic modulus, it is excellent in the vibration of the elastic body. In particular, in the case of a comb-like elastic body in an ultrasonic motor, a non-vibrating body (especially a moving body). The driving force can be improved because the vibration at the tip portion in contact with the surface increases. In addition, the displacement expansion type actuator has an excellent displacement expansion function. For example, when used in a linear motor, the driving force is improved because the vibration at the tip that contacts a non-vibrating body (especially a moving body) increases. it can.

In this specification, the glass transition temperature can be measured according to the DSC method of ASTM 3418.

The density (specific gravity) of the crystalline resin may be, for example, 3 g / cm ³ or less, preferably 0.8 to 2.5 g / cm ³ , more preferably 0.9 to 2 g / cm ³ (particularly 1 About 1.5 g / cm ³ ). If the density is too large, the vibration property is lowered, and the drive transmission property of the moving body is lowered. The density can be measured by a method based on ISO 1183. In the present invention, even if the displacement magnifying element of the displacement magnifying actuator is made of a crystalline resin having a low specific gravity, it has a displacement magnifying function equivalent to or higher than that of an element made of a metal having a high specific gravity. High displacement expansion function.

The crystalline resin is not particularly limited as long as it is a crystalline thermoplastic resin (synthetic resin). For example, olefin resin (cyclic olefin resin such as ethylene-norbornene copolymer), styrene resin ( Syndiotactic polystyrene, etc.), polyacetal resins (such as polyoxymethylene), polyester resins (polyalkylene arylates such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyglycolic acid resins, liquid crystal polyesters, etc.), polybenz Imidazole resins, polyamide resins (aliphatic polyamides, aromatic polyamides, etc.), polyamideimide resins, polyphenylene sulfide resins, polyaryl ketone resins, fluororesins (polytetrafluoroethylene, etc.) Etc., and the like. These crystalline resins can be used alone or in combination of two or more.

Among these crystalline resins, the damping and loss of vibration energy can be suppressed, the displacement expansion function is large, and the engineering plastic can be preferably used because it has excellent heat resistance and wear resistance. For example, syndiotactic polystyrene resin, Aromatic polyamide resins such as nylon MXD6, polyaryl ketone resins, polyphenylene sulfide resins, polyglycolic acid resins, liquid crystal polyesters and the like are widely used.

Furthermore, among these crystalline resins, polyaryl ketone resins, polyphenylene sulfide resins, polybenzimidazole resins, polyamide imide resins, and aromatic polyamide resins are preferable because of their high vibration transmission and displacement expansion functions. In particular, these crystalline resins can be reduced in weight compared to metals and have excellent adhesion to piezoelectric elements. Unlike thermosetting resins, these resins do not contain unreacted curable monomers and can reduce energy loss. Compared with resin, the molecular structure is less likely to be deformed, mechanical loss (tan δ) is small, and energy loss can be reduced. Therefore, in the Langevin vibrator, even when the same current (or voltage) is applied, ultrasonic waves can be transmitted and received with higher efficiency compared to conventional materials.

(1) Polyaryl ketone resin The polyaryl ketone resin is an aromatic polyether ketone having an aryl skeleton bonded by an ether bond and a ketone bond, and is a polyether ketone resin, a polyether ether ketone resin, a polyether ketone ketone. It is classified as a series resin. The aryl skeleton is usually a phenylene group, but has another arylene group such as a substituted phenylene group (for example, an alkylphenylene group having a substituent such as a C _1-5 alkyl group, or a phenyl group). Arylphenylene group) or a group represented by the formula —Ar—X—Ar— (wherein Ar represents a phenylene group and X represents S, SO ₂ or a direct bond). In the aryl skeleton of the polyaryl ketone resin, the ratio of the other arylene group may be, for example, 50 mol% or less (particularly 30 mol% or less). These polyaryl ketone resins can be used alone or in combination of two or more. Of these polyaryl ketone resins, polyether ether ketone resins having a high proportion of ether bonds are preferred from the viewpoint of excellent mechanical properties such as impact resistance.

Polyetheretherketone-based resins are polyetheretherketone obtained by polycondensation of dihalogenobenzophenone and hydroquinone, and are commercially available under the trade name “PEEK” series from VICTREX and “VESTAKEEP” series from EVONIK However, it may be a polyether ether ketone in which the phenylene group has a substituent (for example, a C _1-3 alkyl group), or a polyether ether ketone in which the phenylene group is another aryl skeleton such as a naphthylene group.

The weight average molecular weight of the polyaryl ketone resin (especially polyether ether ketone resin) is, for example, about 5000 to 30000, preferably about 6000 to 25000, and more preferably about 8000 to 20000 in GPC (polystyrene conversion).

Polyaryl ketone resin (especially a polyether ether ketone resin) volume flow rate (MVR) is in compliance with ISO 1133 (380 ℃ / 5kg) , for example, 10 ~ 200cm ^3/10 min, preferably 30 ~ 150 cm ^3/10 min, more preferably about 50 ~ 100 cm ^3/10 min.

Polyaryl ketone resin (especially polyether ether ketone resin) (single resin without filler) can improve vibration transmission in a tensile test (50 mm / min) in accordance with ISO 527-1 / -2 From the following, the tensile strength, breaking strength, yield elongation, breaking elongation, and tensile modulus may be in the following ranges.

That is, the tensile strength may be, for example, about 10 to 300 MPa, preferably about 50 to 200 MPa, and more preferably about 80 to 150 MPa.

The yield elongation may be, for example, about 1 to 10%, preferably 2 to 8%, more preferably about 3 to 6%.

The breaking elongation may be, for example, 10% or more, for example, 10 to 100%, preferably 15 to 50%, and more preferably about 20 to 40%.

The tensile elastic modulus may be, for example, about 1000 to 10,000 MPa, preferably about 2000 to 5000 MPa, and more preferably about 3000 to 4000 MPa.

(2) Polyphenylene sulfide resin As the polyphenylene sulfide resin (polyphenylene thioether resin), homopolymers and copolymers having a polyphenylene sulfide skeleton — (Ar—S) — [wherein Ar represents a phenylene group] Is included. In addition to the phenylene group (—Ar—), the copolymer includes, for example, a substituted phenylene group (for example, an alkylphenylene group having a substituent such as a C _1-5 alkyl group, and an aryl having a substituent such as a phenyl group). Phenyl group) or a group represented by the formula —Ar—X—Ar— (wherein Ar represents a phenylene group and X represents O, SO ₂ , CO, or a direct bond). Good. The polyphenylene sulfide resin may be a homopolymer using the same repeating unit among the phenylene sulfide groups composed of such phenylene groups, and includes different repeating units from the viewpoint of processability of the composition. It may be a copolymer.

As the homopolymer, a substantially linear polymer having a p-phenylene sulfide group as a repeating unit is preferably used. The copolymer can be used in combination of two or more different phenylene sulfide groups. Among these, the copolymer is preferably a combination having a p-phenylene sulfide group as a main repeating unit and an m-phenylene sulfide group. From the viewpoint of physical properties such as heat resistance, moldability and mechanical properties, p-phenylene is preferred. A substantially linear copolymer containing 60 mol% (preferably 70 mol%) or more of sulfide groups is particularly preferable.

The polyphenylene sulfide resin may be a polymer having a relatively low molecular weight linear polymer whose melt viscosity is increased by oxidative crosslinking or thermal crosslinking to improve molding processability, and is reduced from a monomer mainly composed of a bifunctional monomer. It may be a high molecular weight polymer having a substantially linear structure obtained by polymerization. From the viewpoint of physical properties of the obtained molded product, a substantially linear structure polymer obtained by condensation polymerization is preferred. The polyphenylene sulfide resin includes a branched or crosslinked polyphenylene sulfide resin obtained by polymerizing a monomer having three or more functional groups in addition to the polymer, and a resin composition obtained by blending the resin with the linear polymer. Things can also be used.

As the polyphenylene sulfide resin, polyphenylene sulfide (poly-1,4-phenylene sulfide and the like) and polybiphenylene sulfide (PBPS), polyphenylene sulfide ketone (PPSK), polybiphenylene sulfide sulfone (PPSS) and the like can be used. A polyphenylene sulfide resin can be used individually or in combination of 2 or more types.

The number average molecular weight of the polyphenylene sulfide resin is, for example, about 500 to 100,000, preferably 700 to 50,000, and more preferably about 1,000 to 30,000 in GPC (polystyrene conversion).

The melt flow rate (MFR) of the polyphenylene sulfide resin (single resin containing no filler) is compliant with JIS K7315-1 (315 ° C., load 5 kg), for example, 1 to 10000 g / 10 minutes, preferably 5 to It may be about 5000 g / 10 minutes, more preferably about 10 to 3000 g / 10 minutes (particularly 20 to 2000 g / 10 minutes).

Polyphenylene sulfide resin (resin that does not contain a filler) can improve vibration transmission in a tensile test (50 mm / min) in accordance with ISO 527-1 / -2. The elastic modulus may be in the following range.

That is, the tensile strength may be, for example, about 10 to 300 MPa, preferably about 50 to 250 MPa, and more preferably about 60 to 200 MPa.

The breaking elongation may be, for example, about 1 to 30%, preferably 1 to 20%, and more preferably about 1 to 15%.

(3) Polybenzimidazole resin In the polybenzimidazole resin, in addition to polybenzimidazole, part or all of the benzene skeleton is substituted with other aromatic rings (for example, biphenyl ring, naphthalene ring, etc.). In addition to the benzimidazole skeleton, a copolymer unit such as an arylene group such as phenylene may be included. These polybenzimidazole resins can be used alone or in combination of two or more. Of these polybenzimidazole resins, polybenzimidazole is widely used.

(4) Polyamideimide resin The polyamideimide resin is a polymer having an imide bond and an amide bond in the main chain, and a polyamideimide obtained by reacting a tricarboxylic acid anhydride and a polyvalent isocyanate, or a tricarboxylic acid anhydride and a polyvalent amine. May be used to form an imide bond, and then amidated with a polyvalent isocyanate. As the tricarboxylic acid anhydride, trimellitic acid anhydride is usually used. Examples of polyamines and polyisocyanates include polyamines including aromatic amines (phenylenediamine, naphthalenediamine, 2,2-bis (aminophenyl) propane, 4,4′-diaminodiphenyl ether, etc.), aromatic isocyanates ( Polyisocyanates including phenylene diisocyanate, xylylene diisocyanate, tolylene diisocyanate, etc.) are preferred. As the polyamideimide, for example, polyamideimide described in JP-A No. 59-135126 may be used.

(5) Aromatic polyamide resin The aromatic polyamide resin may be a polyamide resin containing an aromatic ring, for example, a polyamide obtained by polymerizing an aliphatic diamine and an aromatic dicarboxylic acid, an aromatic diamine and an aliphatic dicarboxylic acid, And polyamides obtained by polymerizing the above. Examples of the aliphatic diamine include alkylene diamines such as ethylene diamine, hexamethylene diamine, and nonamethylene diamine. Examples of the aromatic diamine include phenylenediamine, metaxylylenediamine, naphthalenediamine, and the like. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, and the like. Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, and phthalic anhydride. Of these aromatic polyamide resins, polyamides obtained by polymerizing C _6-12 alkylene diamines such as hexamethylene diamine and nonamethylene diamine and aromatic dicarboxylic acids such as terephthalic acid are preferable.

Among them, polyaryl ketone resins and polyphenylene sulfide resins are preferable from the viewpoint of excellent heat resistance, wear resistance, and electrical insulation, and polyphenylene sulfide resins are particularly preferable from the viewpoint of excellent bending vibration transmission and displacement expansion function.

The actuator elastic body of the present invention contains a crystalline resin as a main component, and the ratio of the crystalline resin is usually 50% by weight or more (for example, 50 to 100% by weight), preferably 60% with respect to the entire elastic body. % By weight or more (for example, 60 to 99% by weight), more preferably 70% by weight or more (for example, 70 to 95% by weight).

(Filler)
The elastic body of the present invention may contain a filler in addition to the crystalline resin, depending on the application. Combining a crystalline resin and a filler can not only improve mechanical properties such as impact resistance, dimensional stability, and rigidity, but also improve flexural vibration transmission and displacement expansion function. On the other hand, the filler can improve the above characteristics, but when used for a long period of time, the non-vibrating body that comes into contact with the filler may be worn down to reduce the driving force. Therefore, it is preferable that a filler is not substantially included in applications where durability is required, such as a wheel motor.

The filler may be an organic filler or an inorganic filler. The shape of the filler is not particularly limited, either a fibrous filler, or a granular or plate-like filler.

The fibrous filler includes inorganic fibrous fillers and organic fibrous fillers. Examples of inorganic fibrous fillers include ceramic fibers (for example, glass fibers, carbon fibers, asbestos fibers, silica fibers, silica / alumina fibers, zirconia fibers, boron nitride fibers, silicon nitride fibers, potassium titanate fibers, etc.) And metal fibers (for example, stainless steel fibers, aluminum fibers, titanium fibers, copper fibers, brass fibers, etc.). Examples of the organic fibrous filler include high melting point organic fibers such as aramid fibers, fluororesin fibers, and acrylic fibers. These fibrous fillers can be used alone or in combination of two or more.

Examples of granular or plate-like fillers include carbon black, graphite, silicon carbide, silica, silicon nitride, boron nitride, quartz powder, hydrotalcite, glasses (glass flakes, glass beads, glass powder, milled glass fiber, etc.) ), Carbonates (calcium carbonate, magnesium carbonate, etc.), silicates (calcium silicate, aluminum silicate, talc, mica, kaolin, clay, diatomaceous earth, wollastonite, etc.), metal oxides (iron oxide, Titanium oxide, zinc oxide, alumina, etc.), sulfates (calcium sulfate, barium sulfate, etc.), various metal powders, metal foils, and the like. These granular or plate-like fillers can be used alone or in combination of two or more.

These fillers (particularly inorganic fibers) are surface-treated with a sizing agent or a surface treatment agent (for example, a functional compound such as an epoxy compound, an isocyanate compound, a silane compound, or a titanate compound) as necessary. May be. The treatment of the filler may be performed simultaneously with the addition of the filler, or may be performed in advance before the addition. The amount of the sizing agent or surface treatment agent used is 5% by weight or less, preferably about 0.05 to 2% by weight, based on the filler.

Of these fillers, fibrous fillers are preferred because the orientation state can be adjusted to improve the ability to transmit flexural vibrations and the ability to expand displacement, among which inorganic fibers such as glass fibers and carbon fibers, and aramid fibers. Organic fibers such as are widely used, have high heat resistance, can improve vibration transmission, displacement expansion function, and mechanical properties, inorganic fibers are preferred, and carbon fibers are also excellent in lightness and flexibility. Is particularly preferred. The fibrous filler only needs to be at least partially oriented in the elastic body, and includes not only long fibers but also short fibers such as whiskers.

The average fiber diameter of the fibrous filler is, for example, about 0.1 to 50 μm, preferably 1 to 30 μm, and more preferably about 2 to 20 μm. If the fiber diameter is too small, it will be difficult to improve the vibration transmissibility, the displacement expansion function, and the mechanical characteristics. On the other hand, even if the fiber diameter is too large, it is difficult to improve vibration transmission, displacement expansion function, and mechanical characteristics.

The average fiber length of the fibrous filler is, for example, about 1 μm to 2 mm, preferably about 10 μm to 1.5 mm, and more preferably about 100 μm to 1 mm. If the fiber length is too small, it will be difficult to improve vibration transmission, displacement expansion function, and mechanical properties. On the other hand, when the fiber length is too large, it becomes difficult to orient the fibrous filler, and the vibration transmission property and the displacement expansion function are deteriorated.

The average aspect ratio of the fibrous filler is, for example, about 3 to 500, preferably about 5 to 100, and more preferably about 10 to 50. If the aspect ratio is too small, it is difficult to improve vibration transmission, displacement expansion function, and mechanical characteristics. On the other hand, if the aspect ratio is too large, it becomes difficult to orient the fibrous filler, and the vibration transmissibility and the displacement expansion function are reduced.

In this specification, the average fiber diameter of the fibrous filler can be measured by various observation devices such as visual observation, an optical microscope, and a scanning electron microscope (SEM). It is preferable to obtain the value.

The average fiber length was determined by using the above-mentioned observation apparatus from a part (about 500) of fibers obtained by cutting out about 5 g of a sample at random from an arbitrary position of the elastic body, ashing at 650 ° C., and taking out the fibers. .

In the present invention, the fibrous filler is preferably oriented in a certain direction in the elastic body from the viewpoint of improving the flexural vibration transmission property and the displacement expansion function, and the electromechanical conversion element (particularly a piezoelectric element). It is particularly preferred to be oriented parallel to the surface direction of the contact surface between the elastic body and the elastic body (parallel to the vibration direction of the piezoelectric element). The elastic body of the present invention may be formed by laminating a plurality of layers, but the orientation direction of the fibrous filler in each layer is preferably the same direction, and usually the fibrous filler in the single-layer elastic body Are oriented in a certain direction.

The expansion / contraction direction (vibration direction) of the electromechanical conversion element (particularly piezoelectric element) can be appropriately selected. For example, the direction perpendicular to the contact surface between the electromechanical conversion element and the elastic body (in the case of a plate-like piezoelectric element, the thickness) However, the surface direction of the contact surface between the electromechanical transducer and the elastic body (usually the surface direction in the case of a plate-shaped piezoelectric element) is preferable from the viewpoint that bending vibration is easily generated in the elastic body. Further, when the surface shape of the plate-like electromechanical transducer is rectangular, the longitudinal direction is preferable, and in the case of a ring-shaped elastic body (rotor type ultrasonic motor), the circumferential direction is preferable. If the fibrous filler is parallel to the expansion / contraction direction of the electromechanical transducer, the reason why the transmission of bending vibration and the displacement expansion function are improved is not clear, but the fibrous filler is parallel to the expansion / contraction direction. Is oriented in the bending direction on the fibrous filler. Therefore, it is considered that tan δ (loss factor) is reduced by the effect of the fibrous filler, and the characteristics are improved. In particular, it is considered that the ridge-shaped convex portion is easily deformed in the displacement magnifying element. On the other hand, when the orientation direction of the fibrous filler is not parallel to the vibration direction, the rate of deformation of the fibrous filler due to the flexural vibration of the expansion / contraction vibration (driving vibration of the driver) is small, The rate of deformation increases due to variations in the distance between the fibrous fillers. Therefore, it is estimated that the effect of tan δ reduction by the fibrous filler is reduced.

In the case of a ring-shaped elastic body, the vibration direction of the electromechanical conversion element (particularly piezoelectric element) is a direction perpendicular to the contact surface between the electromechanical conversion element and the elastic body from the viewpoint of excellent productivity. Also good.

In the present invention, it is preferable that the AC frequency applied to the electromechanical conversion element (particularly the piezoelectric element) and the resonance frequency in the orientation direction of the fibrous filler in the elastic body to which the electromechanical conversion element is fixed are the same, Tan δ is small. When the resonance frequency is deviated, the ratio of energy input to the elastic body is converted to thermal energy, and the vibration energy electromechanical conversion element transmitted to the non-vibrating body is significantly reduced.

The ratio of the filler (particularly fibrous filler) is, for example, 5 to 100 parts by weight, preferably 10 to 60 parts by weight, more preferably 15 to 50 parts by weight (particularly 20 parts by weight) with respect to 100 parts by weight of the crystalline resin. About 40 parts by weight). When the proportion of the filler is too large, impact resistance and durability are lowered.

The elastic body for actuator of the present invention is substantially formed of a crystalline resin alone or a combination of a crystalline resin and a filler, and the total amount of the crystalline resin and the filler is based on the entire elastic body. In general, it is 80% by weight or more (for example, 80 to 100% by weight), preferably 90% by weight or more (for example, 90 to 99% by weight), more preferably 95% by weight or more (particularly 99% by weight or more), You may form only with crystalline resin and a filler.

(Other additives)
Since the elastic body of the present invention is formed of a crystalline resin, the mechanical properties and design properties can be easily improved by blending a conventional resin additive. Examples of resin additives include colorants (dyes and pigments), lubricants, stabilizers (antioxidants, ultraviolet absorbers, heat stabilizers, light stabilizers, etc.), antistatic agents, flame retardants, and flame retardant aids. , Antiblocking agents, plasticizers, preservatives and the like. These additives can be used alone or in combination of two or more.

[Characteristics and manufacturing method of elastic body]
The elastic body of the present invention can be selected from a range of about 1 to 300 GPa in the tensile elastic modulus in a tensile test (50 mm / min) in accordance with ISO 527-1 / -2. From the point that can be achieved, it may be, for example, about 1.5 to 100 GPa, preferably about 2 to 50 GPa, more preferably about 3 to 10 GPa. If the tensile modulus is too small, the vibration transmission property and the displacement expansion function are lowered, and if the tensile modulus is too large, the molding process becomes difficult.

(Elastic body for ultrasonic motor)
The shape of the elastic body of the present invention can be selected according to the type of actuator (particularly a piezoelectric actuator). For example, in the case of an ultrasonic motor, a two-dimensional shape such as a plate shape (square flat plate shape, disk shape, etc.), a rod shape, etc. It may be a three-dimensional shape such as a shape, a cylindrical shape, a ring shape, or a column shape. In the case of a linear ultrasonic motor, it may be a plate shape or a rod shape (particularly a rod shape), or a rotor type ultrasonic motor. It may be ring-shaped or cylindrical (particularly ring-shaped).

Furthermore, the ultrasonic motor is fixed to the electromechanical conversion element (particularly piezoelectric element) because it can efficiently drive a non-vibrating body (particularly moving body) by bending vibration transmitted from the electromechanical conversion element (particularly piezoelectric element). It is preferable that a convex portion (tooth portion) is formed on the side opposite to the above-mentioned side, and it is particularly preferable that a plurality of convex portions (tooth portions) be formed.

Examples of the planar shape of the convex portion include a quadrangular shape (square shape, rectangular shape, etc.), a triangular shape, a circular shape, and an elliptical shape. Of these shapes, a rectangular shape such as a rectangular shape is preferable. Examples of the cross-sectional shape of the convex portion (cross-sectional shape in the thickness direction of the elastic body) include a quadrangular shape (square shape, rectangular shape, etc.), a triangular shape, and a wave shape. Of these shapes, a rectangular quadrangular shape, a triangular shape, and the like are preferable. In particular, in the case of a linear ultrasonic motor, a triangular shape, in particular, a triangular shape that is asymmetrical in the protruding direction of the convex portion (direction perpendicular to the contact surface between the piezoelectric element and the elastic body) (non-isosceles triangular shape) Such a triangular shape may have a sawtooth shape in which a plurality of such triangular shapes are arranged at intervals. In the case of a rotor type ultrasonic motor, a quadrangular shape, in particular, a quadrangular shape (rectangular shape, square shape, etc.) symmetrical in the protruding direction of the convex portion is preferable.

The number of convex portions may be plural in order to drive the moving body by the bending vibration of the elastic body. In a linear ultrasonic motor, for example, it is about 2 or more (for example, 2 to 10), and the rotor In the type ultrasonic motor, for example, about 10 or more (for example, 10 to 20) convex portions may be regularly formed.

FIG. 6 is a schematic side view showing an example of the linear ultrasonic motor of the present invention, and FIG. 7 is a schematic perspective view of a stator constituting the linear ultrasonic motor of FIG. The motor 41 has a plate-like base portion 43a having a rectangular surface shape and two convex portions (sawtooth portions) 43b formed at a lower portion of the plate-like base portion and extending in the width direction at intervals. The plate-like elastic body 43, the plate-like piezoelectric element 42 laminated on a part of the plate-like elastic body 43 in the length direction, and the tips of the convex portions 43b of the plate-like elastic body are arranged in contact with each other. And a plate-like moving body 45 having the same width as the plate-like elastic body. A pair of

electrodes

42a and 42b for applying a voltage to the piezoelectric element are formed on the surface of the piezoelectric element 42, and a vibrating portion of the piezoelectric element (a portion where the pair of electrodes face each other in the thickness direction of the piezoelectric element). ) And the elastic body 43 coincide with each other. Also in the ultrasonic motor 41, the piezoelectric element 42 and the plate-like elastic body 43 are fixed to form the stator 44, whereas the moving body 45 is movably disposed and is generated by the piezoelectric element 42. The ultrasonic vibration is converted into a linear motion of the moving body 45 via the plate-like elastic body 43. Specifically, when an AC voltage is applied to the piezoelectric element 42 to vibrate in the longitudinal direction, the elastic body expands and contracts in the longitudinal direction along with the vibration of the piezoelectric element on the contact portion side with the piezoelectric element. On the side opposite to the contact portion, the expansion and contraction is suppressed, so that bending vibration occurs, and the convex portion formed on the opposite side is scraped in one direction, and the moving body moves straight in one direction. In particular, by forming the lamination position of the piezoelectric element 42, the formation position of the convex portion 43b of the elastic body, and the triangular shape of the cross section of the convex portion asymmetrically (asymmetric with respect to the central axis in the length direction of the plate-like elastic body), Promotes the above movement.

The shape and size of the elastic body can be selected according to the difference in frequency and type, and is not particularly limited. For example, the elastic body may be prepared within the following range.

In the case of a linear ultrasonic motor as shown in FIG. 6, the elastic body has two or more (for example, 2 to 5, preferably 2 to 3) protrusions having a triangular cross section extending at intervals in the width direction. (More preferably, about two) may be formed, and the triangular section of the convex portion may be a sawtooth shape. The height of the convex portion such as a sawtooth is about 0.5 to 10 mm, preferably about 1 to 8 mm, and more preferably about 2 to 5 mm. The height of the convex portion can be selected according to the frequency, but is 0.1 to 1.5 times, preferably 0.2 to 1.0 times, more preferably 0.3 to 1.0 times the thickness of the elastic body. It is about 0.8 times.

The thickness of the elastic body is, for example, about 1 to 40 mm, preferably 2 to 30 mm, and more preferably about 3 to 20 mm. The thickness of the elastic body is, for example, about 1 to 10 times, preferably 1.5 to 8 times, and more preferably about 2 to 5 times the thickness of the piezoelectric element.

The electromechanical conversion element (particularly the piezoelectric element) is preferably fixed to at least a part of the plate-like elastic body. For example, the length of the elastic body in the longitudinal direction is, for example, 1.5 to 2.5 times (especially 1.8 to 2.2 times) the length of the electromechanical conversion element (length of the vibrating portion). ) Degree. The length of the elastic body in the longitudinal direction may be, for example, about 9 to 200 mm (particularly 15 to 100 mm). The length of the vibration part of the electromechanical transducer may be, for example, about 5 to 100 mm (especially 10 to 50 mm).

The thickness of the elastic body may be, for example, about 0.05 to 0.4 times (particularly 0.1 to 0.3 times) the length in the longitudinal direction. The thickness of the elastic body may be, for example, about 1 to 40 mm (particularly 3 to 20 mm).

Furthermore, it is preferable that the central axis of the elastic body and the vibration part of the electromechanical transducer be approximately aligned with each other from the viewpoint of the transmission of bending vibration.

On the other hand, in the case of a rotor type ultrasonic motor in which the elastic body is ring-shaped, the elastic body has a convex portion for transmitting the bending vibration of the elastic body to the non-vibrating body at the contact portion with the non-vibrating body. The elastic body which does not have the convex part may have vibration transmission properties, but the vibration transmission performance can be improved by forming the convex portions. In the case of a rotor type ultrasonic motor, the elastic body having a convex portion may have a shape (a shape having a comb tooth portion) in which minute convex portions are regularly formed in the circumferential direction of the ring. In the shape having a comb tooth portion, when the convex portion (comb tooth portion) has a quadrangular shape such as a rectangular shape and a slit portion is formed between the convex portions, the width of the convex portion is, for example, 0.1 to It is about 30 mm, preferably about 0.2 to 15 mm, more preferably about 0.5 to 10 mm (particularly 0.5 to 5 mm), and the height of the convex portion is, for example, 0.1 to 30 mm, preferably 0.2. It may be about 15 mm (for example, 0.5 to 10 mm), more preferably about 0.5 to 5 mm (particularly 0.5 to 3 mm). The depth of the slit is, for example, about 0.1 to 30 mm, preferably about 0.2 to 15 mm (for example, 0.5 to 10 mm), more preferably about 0.5 to 5 mm (particularly about 0.5 to 3 mm). It may be. Further, the ratio of the width of the convex portion to the width of the slit portion (the width of the convex portion / the width of the slit portion) is, for example, 0.01 to 100, preferably 0.1 to 10, and more preferably 0.3 to About 30.

The elastic body of the present invention can be manufactured by a conventional molding method, for example, extrusion molding, injection molding, compression molding, etc., depending on the type and shape of the ultrasonic motor. Of these molding methods, extrusion molding, injection molding, and the like are widely used, and in the case of a three-dimensional shape such as a sawtooth shape or a comb tooth shape, the molding can usually be performed by injection molding or cutting. In the present invention, since the elastic body is formed of resin, it is excellent in moldability.

In addition, when the elastic body (in particular, the elastic body of the linear ultrasonic motor) includes a filler, the convex portion of the elastic body may not include the filler. For example, in the case of an elastic body of a linear type ultrasonic motor, the convex portion not including the convex portion is not integrally formed, and the convex portion not including the filler is separately formed by extrusion molding or injection molding, and joined to the plate base of the elastic body. May be.

In particular, as a method of orienting the fibrous filler in a certain direction (particularly a direction parallel to the vibration direction of the piezoelectric element), it is preferable to use extrusion molding or injection molding from the viewpoint of simplicity. In extrusion molding or injection molding, the fibrous filler can be easily oriented in the resin flow direction. The method for orienting the fibrous filler in a certain direction can be appropriately selected depending on the type of resin and is not particularly limited. For example, in extrusion molding, the resin composition to be subjected to melt kneading is 80 to 180 ° C. (particularly 100 ° C.). May be pre-dried at a predetermined time (for example, about 2 to 5 hours) and melt-kneaded at 220 to 420 ° C. (especially 320 to 400 ° C.). In injection molding, the cylinder temperature may be about 220 to 420 ° C. (particularly 320 to 400 ° C.), and the mold temperature may be about 40 to 250 ° C. (particularly 100 to 220 ° C.). Therefore, for the elastic body of the linear ultrasonic motor, a method in which a base part in which the fibrous filler is oriented in the flow direction of the resin is produced by extrusion molding or injection molding, and then a separately produced convex part is joined.

(Displacement magnification element)
When the elastic body of the present invention is a displacement magnifying element of a displacement magnifying actuator, the shape of the displacement magnifying element is a (formable) convex part for forming a gap with a fixed electromechanical piezoelectric element. It has a plate shape. Since the displacement enlarging element has such a convex portion, a gap portion can be formed with the fixed electromechanical piezoelectric element, and the displacement of the convex portion due to expansion and contraction of the electromechanical transducer can be enlarged.

The size of the convex portion can be selected according to the type of the displacement expansion type actuator. The height of the convex portion is such that the height of the void (maximum height) is, for example, 0.1 to 10 mm, preferably 0.2 to 5 mm, more preferably 0.3 to 3 mm (particularly 0.5 to 2 mm). ) Is preferred.

The shape of the convex portion is not particularly limited as long as it can form a gap with the electromechanical piezoelectric element, and is a convex portion for forming (including) a sealed gap with the electromechanical piezoelectric element. There may be a convex portion for forming a void portion that is not sealed with the electromechanical piezoelectric element, such as the convex portion shown in FIG.

Examples of the shape of the convex portion for forming a sealed air gap between the electromechanical piezoelectric element include a hemispherical shape, a conical shape, a truncated conical shape, and a polygonal pyramid shape (triangular pyramid shape, quadrangular pyramid shape, etc.) ), A shape in which a part of the plate surface protrudes into a shape such as a truncated polygonal pyramid shape, a columnar shape, or a polygonal column shape (or a hollow shape that is bent or curved into these shapes). Specifically, the shape of the convex portion may be, for example, the shape described in JP 2012-34019 A.

Among these convex portions, the ridge-shaped convex with both sides open, since the displacement enlargement function is large, the actuator integrated with the electromechanical transducer in injection molding can be easily manufactured, and it is excellent in workability and productivity. A portion (or a mountain-shaped convex portion), that is, a ridge-shaped convex portion extending in one direction formed by bending or bending is preferable.

The cross-sectional shape perpendicular to the ridge direction (ridge direction) of the ridge-shaped convex portion is a bent shape or a curved shape. Examples of the bent shape include a triangular shape, a square shape, a rectangular shape, and a trapezoidal shape. Examples of the curved shape include a substantially semicircular shape and a wave shape. Among these, a trapezoidal shape (particularly, a trapezoidal shape whose width narrows from the contact side with the electromechanical conversion element toward the non-contact side) is preferable from the viewpoint of a large displacement enlarging function. An actuator in which the convex portion has a trapezoidal shape is known as a cymbal actuator.

The height of the ridge-shaped convex portion is such that the height of the void portion (maximum height) is, for example, 0.1 to 5 mm, preferably 0.3 to 3 mm (for example, 0.4 to 2 mm), and more preferably 0. A height of about 5 to 1.5 mm (particularly 0.8 to 1.2 mm) is preferable. The width of the ridge-shaped convex portion (the width in the direction perpendicular to the ridge line direction) is, for example, the width of the void portion (maximum width), for example, 1 to 30 mm, preferably 2 to 20 mm, more preferably 3 to 15 mm. (Especially about 5 to 10 mm). The width of the gap is, for example, 0.1 to 0.9 times, preferably 0.2 to 0.1 times the length of the electromechanical conversion element (particularly the piezoelectric element) (the length in the direction perpendicular to the ridge line direction). It is about 0.8 times, more preferably about 0.3 to 0.7 times. The length of the ridge-like convex portion in the ridge line direction is, for example, about 1 to 100 mm, preferably 2 to 30 mm, and preferably 3 to 20 mm (particularly 5 to 15 mm).

When the cross-sectional shape of the ridge-shaped convex portion is trapezoidal, the inclination angle of the side portion is, for example, 50 to 80 °, preferably 10 to 70 °, more preferably 20 to 60 ° (particularly 30 to 50 °). Degree. If the inclination angle is too large, the width of the vertical movement of the convex portion will be reduced and the displacement expansion function will be reduced. If the inclination angle is too small, it will be difficult to deform the convex portion and the displacement expansion function will be reduced.

The part where the convex part (particularly the ridge-like convex part) is formed is not particularly limited, but it is usually formed in a substantially central part (in the case of a ridge-like convex part, a substantially central part in a direction perpendicular to the ridge line direction).

The planar shape of the displacement enlarging element includes a quadrangular shape (square shape, rectangular shape, etc.), a triangular shape, a circular shape, and an elliptical shape. Of these shapes, a rectangular shape such as a rectangular shape is preferable.

The thickness of the displacement enlarging element is, for example, about 0.3 to 5 mm, preferably about 0.5 to 3 mm, and more preferably about 0.6 to 2 mm (particularly 0.8 to 1.5 mm). The thickness of the displacement enlarging element is, for example, 0.1 to 10 times, preferably 0.3 to 5 times, more preferably 0.3 to 3 times (particularly 0.5 to 3 times) the thickness of the electromechanical transducer element. 2 times).

The displacement magnifying element may have a protrusion when it is used as a drive mechanism that scrapes a non-vibrating body (moving body) in contact therewith. The protrusion is formed on the convex portion of the displacement magnifying element. For example, in the protrusion having the trapezoidal cross-sectional shape, it may be formed on the side as shown in FIG.

The shape of the protrusion may be a polygonal column shape such as a triangular column shape or a quadrangular column shape, a substantially semi-cylindrical shape, a polygonal pyramid shape such as a triangular pyramid shape or a quadrangular pyramid shape. Among these, a polygonal column shape such as a triangular column shape is preferable.

Examples of the cross-sectional shape of the protrusion (in the case of a ridge-like convex portion, a cross-sectional shape perpendicular to the ridge line direction) include, for example, a quadrangular shape (square shape, rectangular shape, etc.), a triangular shape, and a wave shape. Of these shapes, a polygonal shape such as a triangular shape is preferable.

The number of protrusions can be selected according to the type of actuator, and may be singular or plural.

The height of the protrusion is usually 1 or more times the height of the convex portion, for example, 1.2 to 10 times, preferably 1.5 to 8 times, more preferably 2 to 5 times. Degree.

The displacement magnifying element of the present invention can be manufactured by a conventional molding method, for example, extrusion molding, injection molding, compression molding, or the like, depending on the type and shape of the displacement magnifying piezoelectric actuator. Of these molding methods, extrusion molding, injection molding, and the like are widely used, and in the case of a three-dimensional shape such as a sawtooth shape or a comb tooth shape, the molding can usually be performed by injection molding or cutting. In the present invention, since the elastic body is formed of resin, it is excellent in moldability.

In addition, when the displacement magnifying element includes a filler and has a protrusion, the protrusion may not include the filler. For example, in the case of an element having a trapezoidal ridge-like convex section, the ridge-shaped convex portion is formed by extrusion molding, injection molding, or the like separately without forming the projection integrally, and by separately forming the projection not including the filler. You may join to the side part.

When a fibrous filler is contained, a method similar to the method exemplified in the section of the ultrasonic motor elastic body can be used as a method for orienting the fibrous filler in a certain direction. In a displacement magnifying element having protrusions, it is preferable to produce a base having a fibrous filler oriented in the flow direction of the resin by extrusion molding or injection molding, and then join a separately prepared protrusion.

(Elastic body for Langevin vibrator)
When the elastic body of the present invention is an elastic body for a Langevin vibrator, the elastic body forms a resonance member, and the shape of the resonance member is a front member (or front mass) that is a resonance member of a conventional Langevin vibrator, The shape used by a rear member (or rear mass) may be sufficient.

The Langevin transducer (ultrasonic transducer) shown in FIG. 8 is a so-called bolted Langevin transducer and is useful as a device for generating and detecting ultrasonic waves in a medium such as water or air. The Langevin vibrator includes a piezoelectric element 51 and a pair of

resonant members

52 and 53 that sandwich (sandwich) the piezoelectric element. Specifically, the Langevin vibrator includes a piezoelectric element 51, a first resonance member (front member or front mass) 52 that is fixed to one surface of the piezoelectric element and has an ultrasonic transmission / reception unit, and the piezoelectric element. A second resonance member (rear member or rear mass) 53 is provided that is fixed to the other surface of the element and that presses (or pressure-bonds) the first resonance member 52 to the piezoelectric element. Further, in order to prevent the attenuation of ultrasonic waves at the interface and to improve the durability against vibration, the piezoelectric element 51 and the pair of

resonance members

52 and 53 are integrated by a joining means (screw or shaft core bolt or the like) 54. It has become.

In such a Langevin vibrator, when the front member 52 contains a thermoplastic resin and a filler, the surface of the front member 52 can be vibrated at high speed even at a low current (or low voltage).

The piezoelectric element 51 has an electrode plate in addition to the piezoelectric layer in order to apply an alternating voltage oscillated from an oscillator, and is usually a laminate in which piezoelectric layers and electrode plates are alternately and repeatedly stacked. The number of piezoelectric layers and the number of electrode plates are not particularly limited, and are the same or different from each other, for example, 1 to 10, preferably 1 to 8, more preferably 1 to 6 (for example, 1 About 4).

In the example shown in FIG. 8, a circular flaky electrode plate 512 and a disk-shaped piezoelectric layer 511 each having a through hole in the center in the radial direction are inserted through a screw (screw rod) 54 in this order, and three electrode plates A laminated body is formed by interposing two piezoelectric layers 511 between 512. Each of the three electrode plates 512 has a knob 513, and an AC voltage can be applied to the piezoelectric layer 511 by attaching a lead wire to these knobs and connecting to an oscillator (and an amplifier if necessary).

The front member (or front plate) 52 has high adhesiveness with the piezoelectric element 51, can propagate to the tip without attenuating the vibration of the piezoelectric element 51, and can emit strong ultrasonic waves toward the medium. In this example, the front member 52 has a cylindrical shape, and a hole portion having a female screw portion corresponding to the male screw portion of the bonding means 54 is formed on the bonding surface with the piezoelectric element 51. By screwing (or screwing) a screw 54 penetrating the piezoelectric element 51, adhesion to the piezoelectric element 51 is improved, and durability of the piezoelectric element 51 is also improved.

The shape of the front member 52 is not particularly limited, and may be, for example, a columnar shape, a truncated cone shape, a prismatic shape, a truncated pyramid shape, or a hemispherical shape, and a combination of these shapes (the top portion is a truncated cone shape). Or a cylindrical column).

It is not always necessary to provide a hole on the bonding surface with the piezoelectric element 51, but a hole (screw hole) may be formed when bonding is performed by a bonding means such as a screw. The hole is formed in a size that can accommodate a joining member such as a screw. The hole diameter of the hole portion is, for example, about 1 to 60, preferably 5 to 50, and more preferably about 10 to 40, where the length of the front member 52 in the radial direction is 100. The depth of the hole is, for example, about 1 to 70, preferably about 5 to 60, and more preferably about 10 to 50 when the thickness of the front member 52 is 100.

In the present invention, the rear member 53 may be formed of the elastic body of the present invention. However, since the surface of the front member 52 can vibrate at high speed with a low current, the front member 52 is made of the elastic body (thermoplastic resin of the present invention). And an elastic body containing a filler).

The thickness (length in the axial direction) of the front member 52 can be appropriately selected according to the resonance wavelength, and is, for example, about 100 mm or less, preferably 10 to 70 mm, more preferably 20 to 60 mm (for example, 30 to 50 mm). . In the present invention, since the resonance wavelength can be shortened, the thickness of the front member 52 can be reduced and the size can be reduced. The length of the front member 52 in the radial direction is, for example, about 1 to 50 mm, preferably about 5 to 40 mm, and more preferably about 10 to 30 mm.

The acoustic impedance of the front member 52 can be selected from a range of about 1 to 10 N · s / m ³ in accordance with JIS A1405 at room temperature (temperature of about 15 to 25 ° C.), for example, 3 to 9 N · s / m. ³ , preferably 4 to 8 N · s / m ³ , and more preferably about 5 to 7 N · s / m ³ . In the present invention, since the difference in acoustic impedance with a medium such as water or a living body is small, ultrasonic waves can be transmitted and received with high efficiency without reflection of ultrasonic waves at the interface. In addition, the acoustic matching layer is unnecessary, and the apparatus can be miniaturized.

The rear member (or backing plate) 53 sandwiches (sandwiches) the piezoelectric element 51 together with the front member 52, thereby pressing the front member 52 to the piezoelectric element 51. In this example, the rear member 53 has the same shape as the front member 52 and has the same dimensions. The rear member 53 is not limited to the shape and dimensions shown in FIG. 8, and can be changed in design to various shapes and dimensions as with the front member 52.

The thickness ratio between the front member 52 and the rear member 53 is not particularly limited, and can be selected from the range of the former / the latter = 1/3 to 3/1. From the point of emitting ultrasonic waves forward, for example, 1 / It is 1 to 3/1, preferably 1.2 / 1 to 2.8 / 1, more preferably about 1.5 / 1 to 2.5 / 1.

Examples of the main material of the rear member 53 include resins, metals (light metals such as aluminum, magnesium, beryllium, and titanium, heavy metals such as stainless steel), ceramics, and the like. Of these main materials, resins are preferred. The resin may be a thermosetting resin, but is usually a thermoplastic resin. As the thermoplastic resin, for example, in addition to the same resin as the front member 12, (meth) acrylic resin, polyolefin resin (polyethylene resin, polypropylene resin, etc.), polyester resin (polyethylene terephthalate, polyethylene naphthalate) And poly C _2-4 alkylene C _6-10 arylate, etc.), polycarbonate resins, polyamide resins, polyurethane resins and the like.

The main material of the rear member 53 is also preferably a polyphenylene sulfide resin, a polyaryl ketone resin, particularly a polyphenylene sulfide resin, similarly to the front member 52. The resin of the rear member 53 may be the same kind or a different kind of resin as the resin of the front member 52, but is preferably the same kind of resin.

The resin of the rear member 53 may be used in combination with a filler and / or other additives, like the front member 52. Examples of the filler and other additives include the components exemplified in the section of the actuator elastic body, and the preferred components are also the same.

The rear member 53 may have an optional layer (buffer layer, protective layer, etc.) laminated on the surface opposite to the piezoelectric element 51 as necessary.

[Actuator]
The actuator of this invention should just be equipped with the plate-shaped electromechanical transducer which expands-contracts in a surface direction by application of an alternating voltage, and the said elastic body fixed to this electromechanical transducer.

The electromechanical transducer may be an electrostrictive element (or a magnetostrictive element), but a piezoelectric element is preferable from the viewpoint of excellent vibration transmission and displacement expansion function. The piezoelectric element may be a laminated piezoelectric element in order to further improve the displacement expansion function.

Piezoelectric elements are not particularly limited as long as they can generate ultrasonic vibrations, but are not limited to piezoelectric polymer films (fluorine resins such as polyvinylidene fluoride and vinylidene fluoride-trifluoride ethylene copolymers), piezoelectric metal thin films (oxidized) Zinc vapor-deposited film or the like may be used, but it is usually a piezoelectric ceramic layer. The piezoelectric ceramic layer includes ceramics exhibiting piezoelectricity, for example, ABO ₃ type perovskite oxide such as lead zirconate titanate (PZT), lead lanthanum zirconate titanate, lead titanate, and barium titanate. These ceramics can be used alone or in combination of two or more.

The piezoelectric layer 511 may be a piezoelectric polymer film (a fluororesin such as polyvinylidene fluoride or vinylidene fluoride-ethylene trifluoride copolymer), a piezoelectric metal thin film (such as a zinc oxide vapor deposition film), Usually a piezoelectric ceramic layer.

The actuator of the present invention is usually a piezoelectric actuator, and may be, for example, an ultrasonic motor, a displacement expansion type piezoelectric actuator, a Langevin vibrator, or the like.

(Ultrasonic motor)
The ultrasonic motor of the present invention is used in contact with a non-vibrating body, and the elastic body is bent and vibrated (elliptical motion) by the vibration of the electromechanical variable element (particularly the piezoelectric element), so that the elastic body (actuator) itself Alternatively, the non-vibrating body is driven. Examples of the piezoelectric actuator in which the elastic body bends and vibrates include ultrasonic motors such as a rotor type ultrasonic motor and a linear type ultrasonic motor. Among these, the non-vibrating body is a moving body, and a piezoelectric actuator that drives the moving body (in particular, an ultrasonic motor such as a rotor type ultrasonic motor or a linear type ultrasonic motor) is widely used.

In the ultrasonic motor, as the non-vibrating body (moving body), a conventional non-vibrating body, a plate-shaped or rod-shaped moving body (slider), and a rotor (rotating body) can be used depending on the type of the ultrasonic motor. A plate-like moving body used for a linear ultrasonic motor and a rotating body used for a rotor ultrasonic motor are preferable. The material of the non-vibrating body (moving body) is not particularly limited and can be formed of a conventional metal material or resin, and is usually formed of a metal such as stainless steel, aluminum, or brass. A film made of silicone or fluororesin may be formed on the surface of the non-vibrating body (moving body) in order to improve slidability with the elastic body.

As a method for fixing the elastic body and the electromechanical variable element (particularly piezoelectric element), a method of fixing the cut elastic body and the electromechanical variable element with an adhesive, and melting the resin surface of the cut elastic body And a method of fusing the electromechanical variable element, a method of inserting the electromechanical variable element in the mold, and then pouring the molten resin into the mold and sealing the electromechanical variable element (insert molding method). Can be mentioned.

(Displacement expansion type actuator)
The displacement enlarging type piezoelectric actuator of the present invention is an actuator having a mechanism for enlarging displacement due to expansion and contraction of a plate-like electromechanical conversion element that expands and contracts in the surface direction by application of an alternating voltage. What is necessary is just to provide the said displacement expansion element fixed to the electromechanical conversion element. The displacement enlarging element is usually used in contact with a non-vibrating body, and the displacement due to expansion and contraction of the electromechanical transducer is enlarged to drive the displacement enlarging element itself or the non-vibrating body.

In the displacement magnifying element, the plate surface of the displacement magnifying element and the plate-like electromechanical transducer (particularly piezoelectric element) are fixed so as to close at least the concave portion on the back side of the convex portion. It suffices if a gap due to the convex portion is formed between them. As a method of fixing the displacement magnifying element and the electromechanical transducer, for example, a method of fixing the cut displacement magnifying element and the electromechanical transducer using an adhesive, or melting the resin surface of the cut displacement magnifying element. And a method of fusing the electromechanical conversion element, a method of inserting the electromechanical conversion element in the mold and then pouring the molten resin into the mold to seal the electromechanical conversion element (insert molding method). Can be mentioned.

Further, the displacement magnifying element may be fixed to one surface of the plate-like electromechanical transducer, or may be fixed to both surfaces.

When the displacement enlarging element has a convex part for forming a sealed gap with the electromechanical piezoelectric element, the size of the electromechanical conversion element is not particularly limited as long as the sealed gap can be formed. In particular, when the displacement magnifying element is fixed to one surface of the plate-like electromechanical transducer, the size of the electromechanical transducer is preferably smaller than the displacement magnifying element, for example, the diameter of the electromechanical transducer May be about 0.3 to 0.7 times (particularly 0.4 to 0.6 times) the diameter of the displacement enlarging element. On the other hand, when the displacement magnifying element is fixed to both surfaces of the plate-like electromechanical conversion element, the size of the electromechanical conversion element is preferably substantially the same or larger than the displacement magnifying element. The element diameter may be about 0.9 to 1.5 times (particularly 1 to 1.2 times) the diameter of the displacement enlarging element.

When the displacement magnifying element has a ridge-like convex part, the size of the electromechanical conversion element only needs to be able to form a void portion across the ridge-like convex part from the concave side, and the length of the electromechanical conversion element in the ridge line direction is It is about 0.5 to 1.5 times (particularly 0.8 to 1.2 times) the length of the displacement magnifying element, and is generally substantially the same as the length of the displacement magnifying element. Regarding the length in the direction perpendicular to the ridge line direction, when the displacement magnifying element is fixed to one surface of the plate-like electromechanical transducer, the length of the electromechanical transducer is shorter than the displacement magnifying element. Preferably, for example, the length of the electromechanical transducer element may be about 0.3 to 0.7 times (particularly 0.4 to 0.6 times) the length of the displacement enlarging element. On the other hand, when the displacement magnifying element is fixed to both surfaces of the plate-like electromechanical transducer with respect to the length in the direction perpendicular to the ridge line direction, the length of the electromechanical transducer is approximately equal to or greater than the displacement magnifying element. For example, the length of the electromechanical conversion element may be about 0.9 to 1.5 times (particularly 1 to 1.2 times) the length of the displacement enlarging element.

In the displacement magnifying element having a ridge-like convex portion, the length of the displacement magnifying element in the direction perpendicular to the ridge line direction is, for example, 5 to 300 mm, preferably 10 to 100 mm, more preferably 20 to 50 mm (particularly 25 to 40 mm). Degree. The length of the electromechanical transducer in the direction perpendicular to the ridge line direction may be, for example, about 5 to 100 mm, preferably about 10 to 50 mm, and more preferably about 10 to 30 mm.

As the non-vibrating body (moving body), a conventional non-vibrating body, for example, a plate-like or rod-like moving body (slider) such as a linear motor, a rotor (rotating body), or the like can be used. The material of the non-vibrating body (moving body) is not particularly limited and can be formed of a conventional metal material or resin, and is usually formed of a metal such as stainless steel, aluminum, or brass.

Furthermore, it is preferable that the center axis of the displacement enlarging element and the electromechanical transducer element are substantially aligned with each other from the viewpoint of vibration transmission.

(Langujban vibrator)
The Langevin vibrator of the present invention is an actuator that uses a member that reduces the frequency of vibration caused by expansion and contraction of the electromechanical transducer element by a resonance member that sandwiches the electromechanical transducer element. Good.

In the Langevin vibrator shown in FIG. 8, the shape of the piezoelectric layer 511 formed of a piezoelectric element is not particularly limited, and may be, for example, a cylindrical shape, a truncated cone shape, a prismatic shape, a truncated pyramid shape, etc. The shape may be a combination of the above shapes (such as a shape in which a cylinder and a truncated cone are connected in series).

The thickness of the piezoelectric layer 511 can be appropriately selected according to the oscillation frequency, and is, for example, about 500 μm to 10 mm, preferably 1 to 7 mm, and more preferably about 2 to 5 mm.

The shape of the electrode plate 512 is not particularly limited as long as it is a thin piece, and may be a polygon such as a rectangle, a circle, an ellipse, or the like. The electrode plate 512 does not necessarily have a knob, but in order to facilitate the attachment of the lead wire, a knob (extending piece, folded piece, etc.) is provided at the end (or peripheral edge) of the electrode plate 112. ). The thickness of the electrode plate 512 is, for example, about 10 to 500 μm, preferably about 30 to 300 μm, and more preferably about 50 to 150 μm.

The electrode plate 512 may be formed of a conductive material, and examples of the conductive material include metals such as gold, silver, copper, platinum, and aluminum. These conductive materials can be used alone or in combination of two or more.

When the resonant member is bonded with an adhesive, the piezoelectric element 51 (piezoelectric layer 511 and / or electrode plate 512) may not have a hole, but the resonant member may be a screw (or a shaft core bolt) or the like. When the pressure contact means is used, a hole may be formed in the piezoelectric element 51 (piezoelectric layer 511 and / or electrode plate 512). The hole portions may be formed on the joint surfaces of the front member 52 and the rear member 53, and the respective hole portions may be through holes that communicate with each other and penetrate the entire piezoelectric element 51. In addition, the hole part should just be a magnitude | size which can insert joining members, such as a screw | thread.

The resonance frequency of the Langevin vibrator of the present invention can be appropriately selected depending on the application, and is, for example, about 10 to 1000 kHz, preferably about 15 to 900 kHz, and more preferably about 20 to 800 kHz. The ultrasonic transducer may be used at at least one frequency selected from 26, 38, 78, 100, 130, 160, 200, 430, 750, and 950 kHz. In the present invention, the Langevin vibrator can be miniaturized even when applied to an application used at a low frequency.

The current applied to the Langevin vibrator is, for example, about 30 to 250 mA, preferably about 50 to 220 mA, and more preferably about 70 to 210 mA (for example, 80 to 200 mA). In the present invention, even at a low current, the surface can be vibrated at high speed, and ultrasonic waves can be transmitted and received with high efficiency.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. Abbreviations of each component of the materials used in Examples and Comparative Examples are as follows.

[Abbreviations for materials]
PEEK: Polyetheretherketone, “Natural Color (Unfilled)” manufactured by Nippon Extron Co., Ltd., rod-shaped product with a circular cross section, specific gravity 1.45, Tg 143 ° C.
PC1: Bisphenol A-type polycarbonate, “PC (round bar)” manufactured by Shiba Light Co., Ltd., rod-shaped body having a circular cross section, specific gravity 1.2, Tg 160 ° C.
PC2: Polycarbonate, “Polycarbonate round bar” manufactured by Shiraishi Kogyo Co., Ltd.
PPS: Polyphenylene sulfide, “Round bar PPS N” manufactured by Nippon Extron, specific gravity 1.34, glass transition temperature (Tg) 90 ° C.
PMMA: Polymethyl methacrylate, “acrylic cast round bar (transparent)” manufactured by Shiraishi Kogyo Co., Ltd.
CF-containing PPS: Polyphenylene sulfide containing 30% by weight of carbon fibers having an average fiber diameter of about 7 μm, “PPS / CF: black” manufactured by Nippon Extron Co., Ltd., rod-shaped with a circular cross section in which carbon fibers are oriented in the length direction by extrusion molding Molded body, specific gravity 1.45, Tg 90 ° C
CF-containing PEEK: Polyetheretherketone containing 30% by weight of carbon fibers with an average fiber diameter of about 7 μm, “PEEK / CF: Black” manufactured by Nippon Extron Co., Ltd., cross-sectional circle with carbon fibers oriented in the length direction by extrusion molding Rod-shaped body, glass transition temperature (Tg) 143 ° C
GF-containing PA: Nylon MXD6 containing 50% by weight of glass fiber, “MXD-6: Black [Lenny (registered trademark)]” manufactured by Nippon Extron Co., Ltd., having a circular cross section in which glass fibers are oriented in the length direction by extrusion molding Rod-shaped body, specific gravity 1.65, Tg75 ° C
GF-containing PC: Bisphenol A type polycarbonate containing 20% by weight of glass fiber, “PC round bar GF-20 (black)” manufactured by Shiraishi Kogyo Co., Ltd., rod-shaped molding with a circular cross section in which glass fibers are oriented in the length direction by extrusion molding Body, specific gravity 1.41, Tg160 ℃
GF-containing PES: Polyethersulfone containing 30% by weight of glass fiber, “Polyethersulfone round bar GF-30” manufactured by Shiroishi Kogyo Co., Ltd., a rod-shaped product having a circular cross section in which glass fibers are oriented in the length direction by extrusion molding , Specific gravity 1.6, Tg 217 ° C
ABS: ABS resin, “ABS round bar natural” manufactured by Shiraishi Kogyo Co., Ltd., rod shaped body with circular cross section, specific gravity 1.05, Tg 100 ° C.
PE: Polyethylene, “PE Round Bar” manufactured by Shiba Light Coarse Co., Ltd., rod-shaped body with a circular cross section, specific gravity of 0.91, Tg-125 ° C.
Glass epoxy: Epoxy resin containing about 40% by weight of glass fiber with an average fiber diameter of 10 μm, “Epoxy glass (Garaepo) round bar” manufactured by Murakami Electric Co., Ltd.
Aluminum: Alloy standard number A5052
PZT: “C-216” manufactured by Fuji Ceramics.

Using these materials, an ultrasonic motor, a displacement expansion type actuator, and a Langevin vibrator were produced, and the following experiment was conducted.

(A) Experiment on ultrasonic motor [Maximum vibration speed]
An elastic body having the same shape as that of the elastic body 43 shown in FIG. 6 is produced and bonded to a piezoelectric element (piezoelectric vibrator) formed of PZT using an adhesive (“Araldite Standard” manufactured by Huntsman Japan Co., Ltd.). A stator was prepared, and the vibration speed was evaluated using a laser Doppler evaluation apparatus (“AT500-05” manufactured by Graphtec). Specifically, an alternating voltage under resonance conditions is applied to the piezoelectric vibrator and vibrated in the longitudinal direction. At this time, the upper part of the elastic body made of resin expands and contracts, while the lower part where the legs (convex parts) are formed does not expand and contract, so that bending vibration of the stator is realized. By transmitting the bending vibration to the foot, the linear motor advances by the foot catching the ground (non-vibrating body). The vibration speed at this time is evaluated by the evaluation apparatus using the laser Doppler effect, and the resin end portion under the resonance condition (among the sawtooth portion 43b, the central portion of the tip of the sawtooth portion located below the piezoelectric element) The relationship between the maximum vibration speed (vibration speed: mm / second) and the voltage was determined.

The AC voltage generated by the function generator (“WAVE FACTORY 1946” manufactured by NF Circuit Design Block) was boosted by an amplifier (“HSA4101T” manufactured by NF Circuit Design Block) and driven at the resonance frequency. The applied voltage and frequency were adjusted to the most vibrated value for each material and shape.

[Rotation test]
Rotational characteristics were evaluated using the rotor type ultrasonic motor described in FIGS. 1 and 2 or the rotor type ultrasonic motor in which the comb teeth portion is not formed in FIGS. A part of the rotor was marked and rotated, and the rotation characteristics within the unit time of the mark were used as rotational characteristics. The elastic body and the piezoelectric element were bonded using an adhesive (“Araldite Standard” manufactured by Huntsman Japan Co., Ltd.).

An alternating voltage with a phase delayed by 90 ° was sequentially applied to the electrodes adjacent to the electrodes divided into eight. Specifically, the AC voltage generated by the function generator (“WAVE FACTORY 1946” manufactured by NF Circuit Design Block) is boosted by an amplifier (“HSA4101T” manufactured by NF Circuit Design Block) and the phase is 180 ° by the transformer. By separating, four frequency voltages shifted by 90 ° were applied.

The sizes of the two types of rotor type ultrasonic motors are as follows.

(Rotary elastic body without comb teeth)
Piezoelectric vibrator: PZT, inner diameter 6 mm, outer diameter 10 mm, thickness 0.5 mm
Elastic body: inner diameter 4 mm, outer diameter 10 mm, thickness 2 mm
Rotor: made of aluminum, inner diameter 4 mm, outer diameter 10 mm, thickness 5 mm
Power supply: The frequency was adjusted to the value that vibrates most for each material.

(Rotor-type elastic body with comb teeth)
Piezoelectric vibrator: PZT, inner diameter 6 mm, outer diameter 10 mm, thickness 0.5 mm
Elastic body: inner diameter 4 mm, outer diameter 10 mm, thickness 2 mm
Comb shape: slits with a width of 0.5 mm and a depth of 1 mm are formed at equal intervals in 16 locations Rotor: made of aluminum, inner diameter 4 mm, outer diameter 10 mm, thickness 5 mm
Power supply: The frequency was adjusted to the value that vibrates most for each material.

Example 1
PEEK was cut to produce an elastic body having the same shape as the elastic body 43 shown in FIG.

Comparative Example 1
The PC was cut to produce an elastic body having the same shape as the elastic body 43 shown in FIG.

9 shows the results of producing a linear ultrasonic motor using the elastic bodies obtained in Example 1 and Comparative Example 1 and evaluating the maximum vibration speed. As is clear from the results of FIG. 9, the maximum vibration speed when the same voltage was applied was improved in the elastic body of Example 1 as compared with the elastic body of Comparative Example 1.

Example 2
Using CF-containing PPS, the carbon fiber is oriented so that the orientation direction of the carbon fiber is parallel to the contact surface between the piezoelectric element and the elastic body, and parallel to the longitudinal direction of the elastic body, as shown in FIG. An elastic body having the same shape as the elastic body 43 was produced.

Example 3
Using CF-containing PPS, cutting is performed so that the orientation direction of the carbon fiber is perpendicular to the contact surface between the piezoelectric element and the elastic body, and an elastic body having the same shape as the elastic body 13 shown in FIG. 6 is obtained. Produced.

FIG. 10 shows the results of producing a linear ultrasonic motor using the elastic bodies obtained in Examples 2 and 3 and evaluating the maximum vibration speed. As is clear from the results of FIG. 10, the elastic body of Example 2 improved the maximum vibration speed at a higher voltage than the elastic body of Example 3.

Example 4
Using the CF-containing PEEK, cutting is performed so that the orientation direction of the carbon fiber is perpendicular to the contact surface between the piezoelectric element and the elastic body, and the rotor elastic body with comb teeth shown in FIGS. 1 and 2 is obtained. Produced. Using the obtained elastic body, a rotor type ultrasonic motor was produced and subjected to a rotation test. As a result, the rotor was rotated at 1.7 rpm.

Example 5
Using the CF-containing PPS, the orientation direction of the carbon fiber is cut so as to be perpendicular to the contact surface between the piezoelectric element and the elastic body, and the rotor elastic body with comb teeth shown in FIGS. Produced. Using the obtained elastic body, a rotor type ultrasonic motor was manufactured and subjected to a rotation test. As a result, it was rotated at 1.8 rpm.

Example 6
A comb in which the comb-shaped portion is not formed in FIGS. 1 and 2 by cutting using CF-containing PEEK so that the orientation direction of the carbon fiber is perpendicular to the contact surface between the piezoelectric element and the elastic body. A toothless rotor-type elastic body was produced. Using the obtained elastic body, a rotor-type ultrasonic motor was manufactured, and as a result of a rotation test, it was rotated at 0.7 rpm.

Example 7
A comb in which the comb-shaped portion is not formed in FIGS. 1 and 2 by cutting using a CF-containing PPS so that the orientation direction of the carbon fiber is perpendicular to the contact surface between the piezoelectric element and the elastic body. A toothless rotor-type elastic body was produced. Using the obtained elastic body, a rotor-type ultrasonic motor was manufactured and subjected to a rotation test. As a result, it was rotated at 0.8 rpm.

Example 8
A comb in which a comb-tooth portion is not formed in FIGS. 1 and 2 by using GF-containing PA and cutting so that the orientation direction of the glass fiber is perpendicular to the contact surface between the piezoelectric element and the elastic body. A toothless rotor-type elastic body was produced. Using the obtained elastic body, a rotor-type ultrasonic motor was manufactured and subjected to a rotation test. As a result, it was rotated at 0.5 rpm.

Comparative Example 2
The ABS was cut to produce a rotorless elastic body without comb teeth in which the comb teeth portion was not formed in FIGS. Using the obtained elastic body, a rotor type ultrasonic motor was manufactured and a rotation test was performed, but it did not rotate.

(B) Experiment on displacement expansion type actuator [Maximum vibration speed]
A displacement enlarging element 63 having a thickness of 1 mm and having the shape shown in FIG. 11 was manufactured, and a piezoelectric element (thickness 0.5 mm) formed of PZT using an adhesive (“Araldite Standard” manufactured by Huntsman Japan Co., Ltd.) A cymbal type piezoelectric actuator 61 was fabricated by bonding to a piezoelectric vibrator 62. In this actuator, when an AC voltage is applied to the piezoelectric element 62, the piezoelectric element expands and contracts in the longitudinal direction, and the expansion (vibration) is perpendicular to the piezoelectric element surface of the convex portion 63a of the displacement expanding element 63. Converted to vibration (displacement). The vibration velocity in the vertical direction was evaluated using a laser Doppler evaluation apparatus (“AT500-05” manufactured by Graphtec). Further, the maximum vibration speed was read from the amplitude of the vibration speed displayed on the oscilloscope (Tektronix "TDS2014"), and the relationship between the maximum vibration speed and the current was obtained.

Example 9
The PPS was cut to produce a displacement magnifying element having the same shape as the displacement magnifying element 63 shown in FIG.

Example 10
Using a CF-containing PPS, cutting was performed so that the orientation direction of the carbon fibers and the longitudinal direction of the displacement magnifying element were parallel, and a displacement magnifying element having the same shape as the displacement magnifying element 63 shown in FIG. 11 was produced.

Example 11
PEEK was cut to produce a displacement magnifying element having the same shape as the displacement magnifying element 63 shown in FIG.

Example 12
Using a GF-containing PA, cutting was performed so that the orientation direction of the glass fiber and the longitudinal direction of the displacement magnifying element were parallel, and a displacement magnifying element having the same shape as the displacement magnifying element 63 shown in FIG. 11 was produced.

Comparative Example 3
Aluminum was cut to produce a displacement enlarging element having the same shape as the displacement enlarging element 63 shown in FIG.

Comparative Example 4
PC1 was cut to produce a displacement enlarging element having the same shape as the displacement enlarging element 63 shown in FIG.

Comparative Example 5
Using a GF-containing PC, cutting was performed so that the orientation direction of the glass fiber and the longitudinal direction of the displacement magnifying element were parallel, and a displacement magnifying element having the same shape as the displacement magnifying element 63 shown in FIG. 11 was produced.

Comparative Example 6
The ABS was cut to produce a displacement magnifying element having the same shape as the displacement magnifying element 63 shown in FIG.

Comparative Example 7
PE was cut to produce a displacement magnifying element having the same shape as the displacement magnifying element 63 shown in FIG.

The displacement magnifying type piezoelectric actuator was produced using the displacement magnifying elements obtained in the examples and comparative examples, and the maximum vibration speed was measured. Among the measured values, the maximum vibration speed at the current showing the highest value was defined as the maximum speed. Further, Table 1 shows the maximum vibration speed (specific gravity conversion speed) converted per specific gravity for the maximum vibration speed (maximum speed).

As is clear from the results in Table 1, all of the displacement expansion type actuators of the examples were superior in specific gravity conversion speed than the actuators of the comparative examples.

(C) Experiment on Langevin vibrator [Piezoelectric element]
PZT piezoelectric layer (Fuji Ceramics, C-216, thickness 4 mm)
Copper electrode plate (tough pitch copper foil, thickness 100 μm)
[Front mass and rear mass]
Using the materials shown in Table 2, columnar molded bodies each having an outer diameter of 20 mm and a length of 40 mm were used as a front mass and a rear mass.

[screw]
ISO M8, length 40mm
[Ultrasonic transducer]
A vibrator having the same shape as the Langevin vibrator shown in FIG. 8 was produced. That is, the electrode plate 512 and the piezoelectric layer 511 were alternately inserted into the screw 54 to obtain the piezoelectric element 51 (electrode plate 512 / piezoelectric layer 511 / electrode plate 512 / piezoelectric layer 511 / electrode plate 512). It should be noted that the front piezoelectric layer and the rear piezoelectric layer have opposite polarization directions (collision directions). The screw 54 protruding from one surface of the piezoelectric element 51 is screwed into the hole portion of the front mass 52, and the screw 54 protruding from the other surface is screwed into the hole portion of the rear mass 53, so that the piezoelectric element 51 is A Langevin vibrator was obtained by sandwiching and adhering between the front mass 52 and the rear mass 53.

Examples 13 to 15 and Comparative Examples 8 to 11 (Measurement of vibration speed)
The vibration speed of the Langevin vibrators of Examples and Comparative Examples in which the front mass and the rear mass were produced using the materials shown in Table 2 below were evaluated by the experimental system shown in FIG. That is, an alternating voltage oscillating at a resonance frequency was oscillated from an oscillator 55, amplified by an amplifier 56, and applied between electrodes of an ultrasonic vibrator, and the piezoelectric element 51 was vibrated in thickness. The vibration was transmitted to the front mass 52, ultrasonic waves were emitted to the outside, and the vibration speed of the front mass 52 was evaluated using a laser Doppler device 57 (“AT500-05” manufactured by Graphtec). The frequency at which the current maximized was confirmed with the oscilloscope 58, and the frequency was set as the resonance frequency. FIG. 13 shows the applied current dependence of the vibration velocity of the front mass surface evaluated by the experimental system shown in FIG. 12, and Table 2 shows the maximum vibration velocity.

As is clear from FIG. 12 and Table 2, the example can vibrate the vibrator surface at a high speed even at a low current, and the maximum vibration speed is large as compared with the comparative example. For example, although Example 13 is a thermoplastic resin, the maximum vibration speed is higher than that of Comparative Example 9 that is an amorphous resin. Moreover, although Example 14 contains a fiber, its maximum vibration speed is higher than that of Comparative Example 11 which is a thermosetting resin, and is particularly highest as compared with Example 13 which does not contain carbon fiber. The vibration speed is large.

The elastic body of the present invention can be used for actuators such as various electric devices, measuring instruments, and optical devices, in particular, piezoelectric actuators such as ultrasonic motors, displacement expansion type piezoelectric actuators, Langevin vibrators, and the like.

Specifically, the elastic body of the present invention can be used as an ultrasonic motor, for example, a linear type or rotor type ultrasonic motor.

The elastic body of the present invention is a displacement enlarging element of a piezoelectric actuator (particularly, an ultrasonic motor such as a linear ultrasonic motor) that drives a moving body as a displacement enlarging piezoelectric actuator. Available as Further, in applications such as moving a long distance, the displacement magnifying element itself can be used as a displacement magnifying element of a piezoelectric actuator that is a moving body. Furthermore, among displacement expansion type piezoelectric actuators, it is suitable for cymbal type piezoelectric actuators and Mooney type piezoelectric actuators, and is particularly suitable for cymbal type piezoelectric actuators.

Furthermore, the elastic body of the present invention is a Langevin vibrator such as a measuring instrument (flow meter, depth meter, snow cover, etc.), fish detector, probe, cleaning machine, processing machine (cutter, welding machine, etc.) It can be suitably used for a resonance member of a vibrator.

DESCRIPTION OF

SYMBOLS

1,41 ...

Ultrasonic motor

11,21 ...

Piezoelectric actuator

2,12,22,42,51 ... Piezoelectric element 3,43 ...

Elastic body

13,23 ...

Displacement expansion element

13a, 23a ...

Convex part

14,24 ... Gap part 23b ...

Projections

4, 44 ...

Stator

5, 45 ... Moving body 511 ... Piezoelectric layer 512 ... Electrode plate 513 ... Knob 52 ... Front member (front mass)
53. Rear member (rear mass)
54 ... Axle bolt 55 ... Oscillator 56 ... Amplifier 57 ... Laser Doppler device 58 ... Oscilloscope

Claims

An elastic body that is fixed to an electromechanical transducer that expands and contracts by application of an alternating voltage and is used for an actuator according to any one of the following (1) to (3), comprising a crystalline resin.
(1) Actuator that is used in contact with a non-vibrating body, flexurally vibrates due to expansion and contraction of the electromechanical transducer, and drives the actuator itself or the non-vibrating body. (2) Displacement due to expansion and contraction of the electromechanical transducer. Actuator provided with a mechanism for expanding (3) An actuator using a member for reducing the frequency of vibration due to expansion and contraction of the electromechanical transducer as at least one of the resonant members sandwiching the electromechanical transducer
2. The elastic body according to claim 1, wherein the electromechanical transducer is a piezoelectric element.
The elastic body according to claim 1 or 2, wherein the crystalline resin is a polyaryl ketone resin or a polyphenylene sulfide resin.
The elastic body according to any one of claims 1 to 3, further comprising a filler.
The elastic body according to claim 4, wherein the filler is a fibrous filler.
The elastic body according to claim 5, wherein the orientation direction of the fibrous filler is parallel to the expansion / contraction direction of the electromechanical transducer.
6. The fibrous filler is at least one selected from the group consisting of carbon fiber, glass fiber, and aramid fiber, and has an average fiber diameter of 0.1 to 50 μm and an average fiber length of 1 to 2 mm. Or the elastic body of 6.
The elastic body according to any one of claims 4 to 7, wherein a ratio of the filler is 10 to 60 parts by weight with respect to 100 parts by weight of the thermoplastic resin.
The elastic body according to any one of claims 2 to 8, wherein the actuator is an ultrasonic motor and has a plurality of convex portions for contacting the non-vibrating body on the side opposite to the side fixed to the piezoelectric element.
10. The elastic body according to claim 9, wherein the actuator is a linear ultrasonic motor, and the cross-sectional shape of the plurality of convex portions is serrated.
10. The elastic body according to claim 9, wherein the actuator is a rotor type ultrasonic motor and has a comb-tooth portion.
9. The actuator according to any one of claims 2 to 8, wherein the actuator is an actuator having a mechanism for enlarging displacement due to expansion and contraction of the piezoelectric element, and has a plate shape having a convex portion for forming a gap with the fixed piezoelectric element. The elastic body as described in.
The convex portion is a ridge-shaped convex portion formed in a bent or curved shape and extending in one direction, the cross-sectional shape in a direction perpendicular to the ridge line direction of the ridge-shaped convex portion is trapezoidal, and the ridge-shaped convex portion The elastic body according to claim 12, wherein the side portion has a protrusion.
The elastic body according to any one of claims 1 to 8, which is a resonance member of a Langevin vibrator.
A piezoelectric actuator comprising a piezoelectric element and the elastic body according to any one of claims 2 to 14.
16. The piezoelectric actuator according to claim 15, wherein the piezoelectric actuator is a rotor type ultrasonic motor that is used in contact with a rotating body, bends and vibrates due to expansion and contraction of a piezoelectric element, and rotates the actuator itself or the rotating body.
16. The piezoelectric actuator according to claim 15, wherein the elastic body is a displacement enlarging element and is a cymbal type or Mooney type piezoelectric actuator.
15. A Langevin vibrator having a piezoelectric element and a pair of resonance members sandwiching the piezoelectric element, wherein at least one of the pair of resonance members is the elastic body according to claim 14. 15. The piezoelectric actuator according to 15.
19. The piezoelectric actuator according to claim 18, wherein the pair of resonance members includes the same kind of resin, and the piezoelectric element and one resonance member and / or the other resonance member are press-contacted by a joining means.